Output prime numbers less than 1000

for($i = 2; $i < 1001; $i++) {
 $primes = 0;
 for($k = 1; $k <= $i; $ k++)
 if($i%$k === 0) $primes++;
 if($primes <= 2) // An integer that can be divided by 1 and itself (excluding 0)
 echo " {$i}";
}