New puzzle: lucky numbers inspired by codeforces 122A

[akalai]

def sat(d: int, n=6002685529):
    """
    Find a integer factor of n whose decimal representation consists only of 7's and 4's.

    Inspired by [Codeforces Problem 122 A](https://codeforces.com/problemset/problem/122/A)
    """
    return n % d == 0 and set(str(d)) <= {"4", "7"}

Solvers, post your solutions in the comments using the following formatting:

<details><summary>Reveal solution</summary>

```python
def sol():
    return "world"  # replace with your solution
```
</details>