<?php

function isPrime($n){

$isPrime = True;

  for($i = 2; $i <= $n/2; ++$i)
  {
      if($n%$i == 0)
      {
          $isPrime = False;
          break;
      }
  }
  return $isPrime;
}

$number1 = 17;
$number2 = 219339;
$number3 = 37;

echo isPrime($number1)? $number1." is prime number"."<br>" : $number1." is not prime number"."<br>" ;
echo isPrime($number2)? $number2." is prime number"."<br>" : $number2." is not prime number"."<br>" ;
echo isPrime($number3)? $number3." is prime number"."<br>" : $number3." is not prime number"."<br>" ;
?>