Big number in C++

Question

I am trying to place a big number in a C++ variable. The number is 600851475143

I tried unsigned long long int but got an error saying it the constant was too big.

Answer 1

In a more general case when you cannot fit your number in a long long, and can live with the GNU LGPL license (http://www.gnu.org/copyleft/lesser.html), I would suggest trying the GNU Multiprecision Library (http://gmplib.org/).

It is extremely fast, written in C and comes with a very cool C++-wrapper-library.