Where can I see all the administrators of my company?

It's very simple, it'll only take two seconds.

1. Access an administrator's account
2. Go to the section of Company
3. Click on "Permissions"

In the permissions section, you'll find the Administrators group and the default group, plus any permission groups you or any of the administrators on the account have added. 

Click on Administrators > See group and you will be able to see which administrators are in your company. 

CP9

By the way, you can consult this article if you need to create a new administrator in Factorial.