The Girls, Cats & Legs Puzzle!

Here’s a puzzle for you to try..

There are 7 girls on a bus. Each girl has 7 backpacks. In each backpack, there are 7 big cats. Every big cat carries 7 little cats.

Question: How many legs are there in the bus?
The number of legs is the password to unlock an Excel sheet which I no longer have.
I will post the answer soon, before that if you can check yourself, you will be in the brilliant club.

Cheers
Ajit