No.
Not is an adverb and it can also be a noun.
A verb is a word that describes an action (run, walk, etc), a state of being (exist, stand, etc) or occurrence (happen, become, etc).
A noun is a word that is used to describe a person (man, lady, teacher, etc), place (home, city, beach, etc) or thing (car, banana, book, etc).
An adverb is a word that tells us more about a verb (My dog Fifi barks loudly / Nicola is really beautiful).