callable vs due

callable is not a noun while due is a noun.

Word	Noun	Adjective	Verb	Adverb
callable	No	Yes	No	No
due	Yes	Yes	No	Yes

callable (noun)	due (noun)
	that which is deserved or owed
	a payment that is due (e.g., as the price of membership)

callable (adjective)	due (adjective)
subject to a demand for payment before due date	owed and payable immediately or on demand
	suitable to or expected in the circumstances
	capable of being assigned or credited to
	scheduled to arrive

callable (adverb)	due (adverb)
	directly or exactly; straight