28 vs twenty-eight

28 and twenty-eight both are nouns.

Word	Noun	Adjective	Verb	Adverb
28	Yes	Yes	No	No
twenty-eight	Yes	Yes	No	No

As adjectives, 28 and twenty-eight are synonyms defined as:

Other synonyms of 28 include xxviii.

As nouns, 28 and twenty-eight are synonyms defined as:

28 and twenty-eight: the cardinal number that is the sum of twenty-seven and one

Other synonyms of 28 include XXVIII.

28 (noun)	twenty-eight (noun)
the cardinal number that is the sum of twenty-seven and one	the cardinal number that is the sum of twenty-seven and one

28 (adjective)	twenty-eight (adjective)
being eight more than twenty	being eight more than twenty