#!/usr/bin/perl -w 
use strict; 

for my $test_number (5 .. 1000) {
    next unless ($test_number % 2);
    my ($prime , $factor) = IsPrime($test_number);    
    if ($prime) {
        print "$test_number is prime\n";
    }
    else {
        print "$test_number is not prime - divisible by $factor\n";
    }
}

sub IsPrime {
    my $input = shift;
    my $t_number = 3;
    while ($t_number < sqrt($input)) {
        return (0, $t_number) unless ($input % $t_number);
        $t_number += 2;
    }    
    return 1;
}