<?php

function Division7($iInteger)
{
  $aNumbers = array_reverse(str_split((string)$iInteger));
  $iSummary = 0;
  
  foreach($aNumbers as $iPlace => $iNumber)
    $iSummary += $iNumber * pow(3, $iPlace);
  
  return (bool)($iSummary%7 == 0);
}

var_dump(Division7(7));
var_dump(Division7(14));
var_dump(Division7(3151));

?>