[QUOTE=Batalov;452322]That's a tautology.

What you just wrote is equivalent to: "If a number is not divisible by any prime less than itself, then it is a prime number". Where the first clause is equivalent to the definition of a prime number.

So what you wrote is: "If a number is prime, then it is a prime number". That's profound![/QUOTE]
Yes, It kind of lost its appeal after Charles' counter example. It would have been useless but amusing if OP stood.