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run code in 300+ PHP versions simultaneously
<?php function x($n){for($i=1;$i<=$n;$i++){if($n%$i==0&&$i!=$n){$f[]=$i;echo"$i ";}}array_sum($f)==$n?printf('P'):printf('I');}x(28);

preferences:
39.57 ms | 402 KiB | 5 Q