repayable vs due

repayable is not a noun while due is a noun.

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

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

repayable (adjective)	due (adjective)
subject to repayment	owed and payable immediately or on demand
	suitable to or expected in the circumstances
	capable of being assigned or credited to
	scheduled to arrive

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