[asQuirreL]

How big are we talking? The benchmarks I tried the two numbers in your example, but yes, if you go above 2^53, then you will run into trouble with the naive solution, but that is for correctness reasons, not performance reasons.

[ColinWright]

This is an experiment on aspects of a factoring algorithm ... we're going to be talking about a few hundred digits base 10.

So up to around 10^200 or so, which is around 2^600.

[asQuirreL]

Well yes, that definitely changes the game!!