64-Bit System

[ZiNgA BuRgA]

Are you refering to PHP?
I'm not sure what MySQL does - their integer types are probably fixed (but you can verify from the documentation).
The traditional definition of an integer is 32-bits long, which is probably what MySQL uses.

PHP's integer type is always signed, so a 32-bit PHP will only be able to use signed 32-bit integers (anything outside the range get auto-converted to double precision float).  So in this case, it can't fully address the range of a 32-bit unsigned integer (without using floats).