The following expressions give `True` in the `NumericQ` test:

 Map[NumericQ, {Rational[2, 3], Complex[2, 3], 
 Root[1 + 2 #1 + #1^5 &, 1], RootSum[-7 - 3 #1 + #1^5 &, Sin[#1] &]}]

 (* Out: {True, True, True, True} *)

However the heads `Rational`, `Complex`, `Root` and `RootSum` do not have the attribute `NumericFunction`:

 Attributes[Root]
 (* Out: {NHoldAll, Protected, ReadProtected} *)

... but `NumericQ` still returns `True` when applied to them.

Is there a way to obtain a list of all the possible heads `h` of expressions `h[args]` that do *NOT* have the `NumericFunction` attribute, and yet will give `True` in the test `NumericQ[h[args]]`?