Go to your stats page and look at the heading global. The number in parenthesis is the number of active players (played at least one game in the last 90 days). You can look this up for Daily, Rapid, Blitz, etc. The last time that I looked, it was around 2 million for all variations of play.
Interesting
I think chess.com is less popular to lichess. Lichess has on average 25k users active throughout the day so I'd guess chess.com has 15k
Whats lichess again? I heard about it before the propaganda in ben finegolds voice in his videos got to me.