I just came across this idea of a number derivative and wondered about applications or interesting diagrams. Wikipedia has this to say: https://en.wikipedia.org/wiki/Arithmetic_derivative.
Additional information
The Arithmetic Derivative is not the standard derivative one learns in calculus. Here is a definition and some examples:
http://planet2.math.uwaterloo.ca/arithmeticderivative
The arithmetic derivative n′ of a natural number n is defined by the following rules:
0'=0
1'=0
2'=1
96'=272
p'=1, if p is prime