A book called You Can Count on Monsters, by Richard Evan Schwartz, is designed for children but might also be frighteningly productive for adults to read. Schwartz is a math professor at Brown University.
It’s about numbers and the numbers that compose them. And if that sentence is a little scary, try dipping into the book. You will (probably) find it not at all scary.
The image below shows all the most popular numbers from 1 to 100, with each number’s image showing the numbers that factor into it (click here to get to a bigger, enlargeable and embiggenable version):
BONUS: NPR’s review of the book.