There's a good reason why 1 is not considered prime: it would break the property that numbers can be uniquely factorized into primes (i.e. the fundamental theor

There's a good reason why 1 is not considered prime: it would break the property that numbers can be uniquely factorized into primes (i.e. the fundamental theorem of arithmetic). 1 is not composite either; it is called a "unit". Interestingly, 1 has been considered prime in the past (and 2 has also been excluded): https://cs.uwaterloo.ca/journals/JIS/VOL15/Caldwell1/cald5.pdf https://cs.uwaterloo.ca/journals/JIS/VOL15/Caldwell1/cald5.p...