The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<ctype.h>
#include<stdlib.h>
#include<stdbool.h>
#define N 600851475143
bool prim(int n)
{
int i;
for(i=2; i*i<=n; i++)
{
if(n%i==0)
return false;
}
return true;
}
int main()
{
long long s=sqrt(N);
while(s--)
{
if(s%2!=0 && prim(s) && (N%s==0))
{
printf("%lld\n",s);
break;
}
}
return 0;
}
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Answer:
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6857 |