Check all prime number

prime.php

<?php
$count = 0;
$num = 2;
while ( $count < 15 ){  
    $div_count = 0 ;  
    for ( $i=1; $i<=$num; $i++){
        if (($num%$i)==0) {
            $div_count++;
        }
    }
    if ($div_count < 3){
        echo $num." , ";
        $count = $count+1;
    }
    $num=$num+1;  
}