Some posts in the help forum or bug reports have shown that the 32-bit limitation on some core functions can get annoying.
Here's a simple UDF for a handful of functions built to work on native 64-bit AutoIt integers. It uses a trivial DLL (source attached) to invoke C functions.
It contains the following functions, with a short example.
_Div integer divide, _Mod integer modulus
_BitAnd, _BitOr, _BitXor, BitNot
_BitShift, _SignBitShift, _BitRotate