Find the largest prime factor of the number 600851475143

Find_highest_prime_factor.php

<?php
function find_highest_prime_factor($n)
    {
        for ($i = 2; $i <= $n; $i++)
        {
            if (bcmod($n, $i) == 0) //its a factor
            {
                return max($i, $this->find_highest_prime_factor(bcdiv($n,$i)));
            }
        }
        if ($i == $n)
        {
            return $n; //it's prime if it made it through that loop
        }
    }

   
   $n = 600851475143;
   echo find_highest_prime_factor($n);
   ?>