Every time you visit for the FIRST TIME today... [Part 1]

Post a random function that you made. May be from any project you've done or make one impromptu.

Any QUALITY is allowed. No bullying!

Can /prog/ please rate my Project Euler #3 solution?
I am actually >>15.

#include <stdio.h>
#include <math.h>

int main()
{
unsigned long long int i, factor, number = 600851475143;

for (i = 1; i < number; i++) {
/* The largest factors are equal to the number divided
by the smallest factors. Then just test those large factors
for primality. */
if (isprime(factor = (number / i)) && number % i == 0)
break;
}

printf("%Ld", factor);
}

int >>15
isprime(long long int n)
{
long long int i, sqrt_n;

if (n == 2)
return 1;

/* If even number */
if ((n % 2 == 0) || n <= 1)
return 0;

sqrt_n = sqrt(n);
/* Skip every 2nd number to avoid even numbers
to reduce the number of loops */
for (i = 3; i <= sqrt_n; i += 2) {
if (n % i == 0)
return 0;
}

return 1;
}