### isArmstrongNumber

Checks if the given number is an Armstrong number or not.

Convert the given number into an array of digits. Use `Math.pow()` to get the appropriate power for each digit and sum them up. If the sum is equal to the number itself, return `true` otherwise `false`.

```js
const isArmstrongNumber = digits =>
  (arr => arr.reduce((a, d) => a + Math.pow(parseInt(d), arr.length), 0) == digits)(
    (digits + '').split('')
  );
```

```js
isArmstrongNumber(1634); // true
isArmstrongNumber(371); // true
isArmstrongNumber(56); // false
```