In Response To 'Re: Re: How to control the format of the answer'
The traditional limit on the number of digits in an Integer in Mathematica has been 2^31.
It might be higher in recent 64-bit Mathematicas, but the memory and time resources
are likely to run out before the calculation gets close to that.
If you try to print out the number or save it to a text file, remember that
formatting a number takes more memory than storing it internally.