心理学 (しんりがく) = psychology
Haha, that’s quite a coincidence, as German happens to be my first language!
I think one of the most interesting fact about e is that it appears in so many branches of Mathmatics, even if they don’t seem to be related at all! And then there are multiple ways to define e (e.g. with a series or a limit).
And there is a pretty interesting fact about pi, too! I’ve learned and noticed that whenever pi shows up somewhere, there is pretty much always some way to find a hidden circle where the pi comes from. I don’t know if there is an exception to that, but I haven’t found one yet 
Apart from these, some other very interesting numbers that I can think of right now are phi (aka golden ratio), 42 (cuz funny lol), i (I love working with complex numbers 
), and the omega constant (because it is defined via one of my favorite functions when it comes to solving equations 
).
