why wont it run???

3.cpp

/*
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>
#include<stdint.h>

using namespace std;

int main(){
    cout << "Enter upto which number yuou want to check prime numbers ";
    unsigned long long int  limit=600851475143, factor_count=0;
    for (long long i = limit; i >= limit/1000; i--)
    {
        factor_count=0;
        // cout << " " << i << " ";
        for (long long j = 2; j < i; j++)
        {
            if(i%j==0)
            {
                ++factor_count;
            }            
        }
        if (factor_count==0 )//&& limit%i==0)
        {
            cout << "  " << i ;
          
            if(limit%i==0)
            {
                cout << "LARGST = " << i;
                break;
            }   
            
        }
        
        
    }
    cout<<"prime number out" << limit<<"\n";
    
}