I think you meant 31, assuming that as people have stated it is around 2.1bil, then I work it out to be to the 31, it's a 31 bit value. Weird, dunno why it isn't 32, I'd have expected that, maybe it was just to save a bit of space. Although, theres something i'm missing, it could be (2^31)+1, which'd make it 32 bits long?