What are all of the speed numbers for a bike?
While not everything is commonly available new now, every number from 1 to 33 has been found on new bikes except 13, 17, 19, 23, 25, 26, 28, 29, 31, and 32. If you start counting quad chainring setups and internal hubs with clusters hacked on to them you get access to a bunch of other weird numbers.

Note that looking at the number of speeds itself is basically trivia. The gearing range and the interval between available gears tell an equally or more important part of the story.