The easiest way of determining whether a "small number" is a prime, is to look it up. Here you find the first 50 million primes (up to 982451653). Since 4294967311 exceeds 982451653, grab the primes up to 65536 (which count less than 10000), and divide 4294967311 by them. 4294967311 is prime if and only if none of the primes less than 65536 divides 4294967311 properly.