$s = "#22aantal283xuitvoeren";
preg_match_all("/d+/", $s, $number);
echo end($number[0]); // 283

$string = "#22aantal283xuitvoeren";

$result = preg_match_all(
    "/(d+)/",
    $string,
    $matches);

    $lastNumericValueInString = array_pop($matches[1]);

    echo $lastNumericValueInString;