In the maintenance page, go to
Check/maintain virtual classes
If server says "There are many virtual classes on this site" then enter some keyword (a few letters, maybe your name if you have a class) just to restrict the number of corresponding classes. Now you see a small list of classes.
Then clic on "Show best class activity on this period. " and you'll get, above the table, the total number of classes.
I don't think there is a tool to show all class names if there are many of them. But of course you may inspect the log/classes directory on the server directly (maintenance / direct file management). All numbers below 10000 are example classes (the same on all servers), other are "real" classes on your own server.
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