Stack Overflow has just surpassed 1000000 users user ids. Yet if you go to the /users
page, there are "only" 15655 pages. 36 users a page, that's "only" 563,580 users.
Since unregistered users also have their unique ids but don't show up in the /users
pages, I'll assume there is difference there. But are about half of our members unregistered?
And there are users who are outright deleted. What gives? Does SO purge its users after some period of inactivity?