Actually since these are signed longs it only goes up to 2^31-1, which is a prime, a Mersenne Prime actually. (For those that missed this bit, a Mersenne prime is any prime expressable in the form 2^N-1.)

I dont know if I'm the only one that finds it interesting that the highest number you can represent with a long is a prime, but I do. :-)

Now if only they would use questions like this on pub-quizzes. :-)