Let's see how fast I can do this:
9 Creation and other Genesis panels
4 Old Testament scenes in the corner pendentives
8 spandrel scenes depicting the Ancestors of Christ
12 Prophets and Sibyls
That's 33 panels, but the 14 lunettes (also depicting Ancestors of Christ) at the tops of the walls are usually included. There used to be 16, but Michelangelo himself sanctioned the destruction of 2 on the west (altar) wall, to make way for the "Last Judgment."
Then there are 20 Ignudi, along with assorted bronze nudes, putti, caryatids, and subsidiary Old Testament scenes flanking the Genesis scenes. Altogether, the ceiling involves over 300 figures.
The text in this site is poor, but the diagram isn't bad, though it doesn't include the lunettes. Click to enlarge: