popular vs popularity

popular is not a noun while popularity is a noun.

Word	Noun	Adjective	Verb	Adverb
popular	No	Yes	No	No
popularity	Yes	No	No	No

popular (noun)	popularity (noun)
	the quality of being widely admired or accepted or sought after

popular (adjective)	popularity (adjective)
regarded with great favor, approval, or affection especially by the general public
carried on by or for the people (or citizens) at large
(of music or art) new and of general appeal (especially among young people)
representing or appealing to or adapted for the benefit of the people at large