Does that mean that there have been 4627 threads deleted?? That's over one in five threads that does not make it. I'm concerned for the lives of these threads... They have a high mortality rate.
So, if somewhere, a post is deleted, then there can be another 20,000th thread? Delicious. Meh - this means that it's almost at 25,000, which is much better than 20,000 anyway.