First of all, what's so big in storage of such big integers. This is a little more than 2K you need for storage, plus some overhear for implementation. Not too big, really. But of course, standard CPU numeric types won't help here.
What you need is called "big integer class". Please see, for example, this open-source implementation:
http://sourceforge.net/projects/cpp-bigint/[
^].
You can find some more:
http://bit.ly/14mQCGc[
^].
—SA