Largest prime factor | Project Euler | Problem #3

URL to the problem page: https://projecteuler.net/problem=3

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143?

#include <iostream>

using namespace std;

int main()

{

    long long number = 600851475143, a, i, counter, j;

    for (i = 2; ; i++) {

        a = number / i;

        counter = 0;

        if (number % a == 0) {

            for (j = 2; j <= sqrt(a); j++) {

                if (a % j == 0) {

                    counter++;

                    break;

                }

            }

            if (counter == 0) {

                cout << "Largest prime factor of " << number << " is  =  " << a << endl;

                break;

            }

        }

    }

    return 0;

}



CLICK TO SEE THE OUTPUT.