In this code below, it is supposed to take a number and reverse it

I tried to do it without `num = num + ""` but it does not work

why do I need to add that before I split the number ?

```
function reverseANumber(num) {

    function reverse() {

        num = num + "";
        var newNum;
        newNum = num.split("").reverse().join();
        return newNum;
    }
    return reverse(num);
}

console.log(reverseANumber(34521));

```