PIN number vs PIN

PIN number and PIN both are nouns.

Word	Noun	Adjective	Verb	Adverb
PIN number	Yes	No	No	No
PIN	Yes	No	No	No

As nouns, PIN number and PIN are synonyms defined as:

PIN number and PIN: a number you choose and use to gain access to various accounts

Other synonyms of PIN number include personal identification number.

PIN number (noun)	PIN (noun)
a number you choose and use to gain access to various accounts	a number you choose and use to gain access to various accounts