Convert large numbers into a more readable format

It can be tricky to really understand the value of 7312946 or 983217 at the first glance. Saying 7.3M and 983k seems like a much better option. How to convert numbers into a nicer format? Like this:

/**
 * create a nicely formatted number
 * @param $number a large number
 * @param $shorten default true = append k or M, false = format with commas and dots
 * @return int
 */
function createHumanReadableInteger($number, $shorten = true) {
	if (is_numeric($number)) {
		if ($shorten) {
			if ($number < 100000) {
				$return_int = number_format($number, 0);
			} else {
				$number_proc = $number;
				$units = explode(" ", "B k M G T P");
				for ($i = 0; $number_proc > 1000; $i++) {
					$number_proc = $number_proc / 1000;
				}
				if ($number > 1000000) {
					$return_int = round($number_proc, 2) . " " . $units[$i];
				} else {
					$return_int = round($number_proc, 1) . " " . $units[$i];	
				}
			}
		} else {
			$return_int = number_format($number, 0);
		}
		return $return_int;	
	} else {
		return 0;
	}
}