changeless vs invariable

changeless is not a noun while invariable is a noun.

Word	Noun	Adjective	Verb	Adverb
changeless	No	Yes	No	No
invariable	Yes	Yes	No	No

changeless (noun)	invariable (noun)
	a quantity that does not vary

changeless (adjective)	invariable (adjective)
not subject or susceptible to change or variation in form or quality or nature	not liable to or capable of change
unvarying in nature
remaining the same for indefinitely long times