Find the largest prime number factor?

Question

I need to find The prime factors of 13195 are 5, 7, 13 and 29. / * Largest is 377. * / What is the largest prime factor of the number 600851475143 ?

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Answer 1

600851475143 is probably above the precision of your platform's long data type. It requires at least 40 bits to store. You can use this to figure out how many bits you have:

#include 

printf("my compiler uses %u bits for the long data type\n", (unsigned int) (CHAR_BIT * sizeof (long)));