1 could be a prime, too, as for example Legendre, Lesbegue, Cayley (in the Encyclopædia Britannica), Kronecker, Hardy and Sagan stated at least once (see the URL I linked to earlier)

One isn't typically called a prime for the same reason as mathematicians typically say 0^0 equals 1; it makes many theorems and proofs look better.

Hm. I'm a mathematician. I always thought it wasn't called prime because it breaks uniqueness for the fundamental theorem of arithmetic.

It makes it look pret29th!