diff --git a/pint/delegates/formatter/html.py b/pint/delegates/formatter/html.py
index 263a01155..531f2933f 100644
--- a/pint/delegates/formatter/html.py
+++ b/pint/delegates/formatter/html.py
@@ -10,16 +10,18 @@
 
 from typing import TYPE_CHECKING
 import re
+from functools import partial
 from ...util import iterable
 from ...compat import ndarray, np, Unpack
 from ._helpers import (
     split_format,
     formatter,
+    join_mu,
 )
 
 from ..._typing import Magnitude
 from ._unit_handlers import BabelKwds, format_compound_unit
-from .plain import DEFAULT_NUM_FMT
+from .plain import format_number
 
 if TYPE_CHECKING:
     from ...facets.plain import PlainQuantity, PlainUnit, MagnitudeT
@@ -38,25 +40,23 @@ def format_magnitude(
             assert isinstance(mstr, str)
         else:
             if isinstance(magnitude, ndarray):
-                # Use custom ndarray text formatting with monospace font
-                formatter = f"{{:{mspec or DEFAULT_NUM_FMT}}}"
                 # Need to override for scalars, which are detected as iterable,
                 # and don't respond to printoptions.
                 if magnitude.ndim == 0:
-                    mstr = formatter.format(magnitude)
+                    mstr = format_number(magnitude, mspec)
                 else:
-                    with np.printoptions(formatter={"float_kind": formatter.format}):
-                        mstr = (
-                            "<pre>" + format(magnitude).replace("\n", "<br>") + "</pre>"
-                        )
+                    with np.printoptions(
+                        formatter={"float_kind": partial(format_number, spec=mspec)}
+                    ):
+                        mstr = "<pre>" + format(magnitude).replace("\n", "") + "</pre>"
             elif not iterable(magnitude):
                 # Use plain text for scalars
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = format_number(magnitude, mspec)
             else:
                 # Use monospace font for other array-likes
                 mstr = (
                     "<pre>"
-                    + format(magnitude, mspec or DEFAULT_NUM_FMT).replace("\n", "<br>")
+                    + format_number(magnitude, mspec).replace("\n", "<br>")
                     + "</pre>"
                 )
 
@@ -108,7 +108,8 @@ def format_quantity(
         else:
             joint_fstring = "{} {}"
 
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )
diff --git a/pint/delegates/formatter/latex.py b/pint/delegates/formatter/latex.py
index 3c3db69cd..fb199cbd6 100644
--- a/pint/delegates/formatter/latex.py
+++ b/pint/delegates/formatter/latex.py
@@ -17,7 +17,8 @@
 from ..._typing import Magnitude
 from ...compat import ndarray, Unpack, Number
 from ._unit_handlers import BabelKwds, override_locale, format_compound_unit
-from .plain import DEFAULT_NUM_FMT
+from ._helpers import join_mu
+from .plain import format_number
 
 if TYPE_CHECKING:
     from ...facets.plain import PlainQuantity, PlainUnit, MagnitudeT
@@ -142,9 +143,9 @@ def format_magnitude(
     ) -> str:
         with override_locale(babel_kwds.get("locale", None)):
             if isinstance(magnitude, ndarray):
-                mstr = ndarray_to_latex(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = ndarray_to_latex(magnitude, mspec)
             else:
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT).replace("\n", "")
+                mstr = format_number(magnitude, mspec)
 
             mstr = _EXP_PATTERN.sub(r"\1\\times 10^{\2\3}", mstr)
 
@@ -181,7 +182,8 @@ def format_quantity(
 
         joint_fstring = r"{}\ {}"
 
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )
@@ -193,11 +195,12 @@ def format_magnitude(
     ) -> str:
         with override_locale(babel_kwds.get("locale", None)):
             if isinstance(magnitude, ndarray):
-                mstr = ndarray_to_latex(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = ndarray_to_latex(magnitude, mspec)
             else:
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT).replace("\n", "")
+                mstr = format_number(magnitude, mspec)
 
-            mstr = _EXP_PATTERN.sub(r"\1\\times 10^{\2\3}", mstr)
+            # TODO: Why this is not needed in siunitx?
+            # mstr = _EXP_PATTERN.sub(r"\1\\times 10^{\2\3}", mstr)
 
         return mstr
 
@@ -215,10 +218,14 @@ def format_unit(
 
         # TODO: not sure if I should call format_compound_unit here.
         # siunitx_format_unit requires certain specific names?
+        # should unit names be translated?
+        # should unit names be shortened?
+        # units = format_compound_unit(unit, uspec, **babel_kwds)
 
-        units = format_compound_unit(unit, uspec, **babel_kwds)
+        formatted = siunitx_format_unit(unit._units.items(), registry)
 
-        formatted = siunitx_format_unit(units, registry)
+        # TODO: is this the right behaviour? Should we return the \si[] when only
+        # the units are returned?
         return rf"\si[]{{{formatted}}}"
 
     def format_quantity(
@@ -233,9 +240,8 @@ def format_quantity(
             qspec, registry.default_format, registry.separate_format_defaults
         )
 
-        joint_fstring = r"{}\ {}"
+        joint_fstring = "{}{}"
 
-        return joint_fstring.format(
-            self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
-            self.format_unit(quantity.units, uspec, **babel_kwds),
-        )
+        mstr = self.format_magnitude(quantity.magnitude, mspec, **babel_kwds)
+        ustr = self.format_unit(quantity.units, uspec, **babel_kwds)[len(r"\si[]") :]
+        return r"\SI[]" + join_mu(joint_fstring, "{%s}" % mstr, ustr)
diff --git a/pint/delegates/formatter/plain.py b/pint/delegates/formatter/plain.py
index 4e1dd9a6b..a6dab74ef 100644
--- a/pint/delegates/formatter/plain.py
+++ b/pint/delegates/formatter/plain.py
@@ -7,14 +7,16 @@
 """
 
 from __future__ import annotations
+from functools import partial
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 import re
 from ...compat import ndarray, np, Unpack
 from ._helpers import (
     _pretty_fmt_exponent,
     split_format,
     formatter,
+    join_mu,
 )
 
 from ..._typing import Magnitude
@@ -25,7 +27,21 @@
     from ...facets.plain import PlainQuantity, PlainUnit, MagnitudeT
 
 
-DEFAULT_NUM_FMT = ".16n"
+def format_number(value: Any, spec: str = "") -> str:
+    if isinstance(value, float):
+        return format(value, spec or ".16n")
+
+    elif isinstance(value, int):
+        return format(value, spec or "n")
+
+    elif isinstance(value, ndarray) and value.ndim == 0:
+        if issubclass(value.dtype.type, np.integer):
+            return format(value, spec or "n")
+        else:
+            return format(value, spec or ".16n")
+    else:
+        return str(value)
+
 
 _EXP_PATTERN = re.compile(r"([0-9]\.?[0-9]*)e(-?)\+?0*([0-9]+)")
 
@@ -56,8 +72,8 @@ def format_quantity(
         )
 
         joint_fstring = "{} {}"
-        print(repr(mspec), repr(uspec))
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )
@@ -71,11 +87,12 @@ def format_magnitude(
             if isinstance(magnitude, ndarray) and magnitude.ndim > 0:
                 # Use custom ndarray text formatting--need to handle scalars differently
                 # since they don't respond to printoptions
-                formatter = f"{{:{mspec or DEFAULT_NUM_FMT}}}"
-                with np.printoptions(formatter={"float_kind": formatter.format}):
+                with np.printoptions(
+                    formatter={"float_kind": partial(format_number, spec=mspec)}
+                ):
                     mstr = format(magnitude).replace("\n", "")
             else:
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = format_number(magnitude, mspec)
 
         return mstr
 
@@ -107,8 +124,8 @@ def format_quantity(
         )
 
         joint_fstring = "{} {}"
-        print(repr(mspec), repr(uspec))
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )
@@ -122,11 +139,12 @@ def format_magnitude(
             if isinstance(magnitude, ndarray) and magnitude.ndim > 0:
                 # Use custom ndarray text formatting--need to handle scalars differently
                 # since they don't respond to printoptions
-                formatter = f"{{:{mspec or DEFAULT_NUM_FMT}}}"
-                with np.printoptions(formatter={"float_kind": formatter.format}):
+                with np.printoptions(
+                    formatter={"float_kind": partial(format_number, spec=mspec)}
+                ):
                     mstr = format(magnitude).replace("\n", "")
             else:
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = format_number(magnitude, mspec)
 
         return mstr
 
@@ -159,7 +177,8 @@ def format_quantity(
 
         joint_fstring = "{} {}"
 
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )
@@ -173,11 +192,12 @@ def format_magnitude(
             if isinstance(magnitude, ndarray) and magnitude.ndim > 0:
                 # Use custom ndarray text formatting--need to handle scalars differently
                 # since they don't respond to printoptions
-                formatter = f"{{:{mspec or DEFAULT_NUM_FMT}}}"
-                with np.printoptions(formatter={"float_kind": formatter.format}):
+                with np.printoptions(
+                    formatter={"float_kind": partial(format_number, spec=mspec)}
+                ):
                     mstr = format(magnitude).replace("\n", "")
             else:
-                mstr = format(magnitude, mspec or DEFAULT_NUM_FMT)
+                mstr = format_number(magnitude, mspec)
 
             m = _EXP_PATTERN.match(mstr)
 
@@ -217,7 +237,8 @@ def format_quantity(
 
         joint_fstring = "{} {}"
 
-        return joint_fstring.format(
+        return join_mu(
+            joint_fstring,
             self.format_magnitude(quantity.magnitude, mspec, **babel_kwds),
             self.format_unit(quantity.units, uspec, **babel_kwds),
         )