Currently, multiplicative functions are only briefly introduced here. However, this kind of functions is quite important in competitive programmings. Some examples are Euler totient function, mobius function,...

There are 2 excellent blog about multiplicative functions on Codeforces:

• https://codeforces.com/blog/entry/54090
• https://codeforces.com/blog/entry/53925

I think we should merge these blogs into a dedicated article on CP-Algorithms (of course with credits to original author). What's your opinion about this?