number 1 vs number one

number 1 and number one both are nouns.

Word	Noun	Adjective	Verb	Adverb
number 1	Yes	No	No	No
number one	Yes	No	No	No

As nouns, number 1 and number one are synonyms defined as:

Other synonyms of number 1 include first.

number 1 (noun)	number one (noun)
the first element in a countable series	a reference to yourself or myself etc.; `take care of number one' means to put your own interests first
	the first element in a countable series
	the first or highest in an ordering or series