freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-429-sum-of-squares-of-unitary-divisors.md

---
id: 5900f5191000cf542c51002c
title: 'Problem 429: Sum of squares of unitary divisors'
challengeType: 5
forumTopicId: 302099
dashedName: problem-429-sum-of-squares-of-unitary-divisors
---

# --description--

A unitary divisor d of a number n is a divisor of n that has the property gcd(d, n/d) = 1.

The unitary divisors of 4! = 24 are 1, 3, 8 and 24.

The sum of their squares is 12 + 32 + 82 + 242 = 650.

Let S(n) represent the sum of the squares of the unitary divisors of n. Thus S(4!)=650.

Find S(100 000 000!) modulo 1 000 000 009.

# --hints--

`euler429()` should return 98792821.

```js
assert.strictEqual(euler429(), 98792821);
```

# --seed--

## --seed-contents--

```js
function euler429() {

  return true;
}

euler429();
```

# --solutions--

```js
// solution required
```