Ammon Lauritzen - 2008-04-26 17:23:50 - In reply to message 1 from Alex Lau
That is correct, the definition of a prime number is that which is cleanly divisible only by one and itself. Imaginary numbers cannot be prime.
The reason one is not prime is because every number has a unique and distinct factorization into primes. In other words, 30 = 2 x 3 x 5. If one were prime, these factorizations would go on forever, 30 = 1^inf x 2 x 3 x 5.