After looking back to the beginning of chapter 3, I saw Pythagoras's name early in the chapter. Then I got to thinking about this later. I wondered why his name was in our Number Theory book as I think of the Pythagorean Theorem (or a more algebra or geometry based course) when I hear the name Pythagoras. So I went and did a little research on him. I found that his basis of the Pythagorean Theorem is what made his followers (the Pythagoreans) so fascinated in numbers. They believed that numbers "constitute the nature of all things." However, after looking in the book, it says that the Pythagoreans kept most all of their findings and information to themselves. So, it is believed that many of the concepts of amicable, perfect, deficient, and abundant numbers may have originally been the findings of the Pythagoreans even though they aren't really accredited to them.

Also, not quite as related as what was said above, but when I was looking for information on this, I came across a website that said Pythagoras thought of odd numbers and male numbers and even numbers as female numbers. I've never heard that before and find it interesting. However, the website doesn't say why Pythagoras thought of numbers that way.