One good use for Python's OOP is operator overloading. Since Python doesn't have type signatures, you can't overload the "plus" operator with a free function like you can in C++. Writing numerical code without operator overloading is painful.
You are using Python's class mechanism, but that's where the OOness ends. The types themselves are immutable value types, carrying no state and reacting to no messages, and they don't exploit a class hierarchy beyond having a common "Number" class. The "methods" don't even behave like methods, e.g. __add__(self, other) has special wiring so it obscures which side of the addition is "self".
That's very different than a classic OO scheme like a UI toolkit.
