Write a program to find the factorial of a number in PHP?

The program to find the factorial of a number in PHP is:

<?php

function Factorial($number){

    if($number <= 1){  

        return 1;  

    }  

    else{  

        return $number * Factorial($number - 1);  

    }  

}

$number = 20;

$fact = Factorial($number);

echo "Factorial = $fact";

?>