Number of participants

Is it possible to overview the number of participants from a past meeting, counting all who were actively participating with micro/camera and the ones who just watch the meeting without activities ?

If you have a service like Callstats or ObserveRTC, you can get such historic info. Otherwise I’m not sure you’ll find everything in the logs, but they can also be an option. You may also have trouble identifying each user.
All of this is, of course, if you mean your own deployment. If you mean the public service, there is no such stats provided.

P.S. Now I see you mean not a stats of the activities, but just a total number of the participants - this can be found in the logs.