I'm debating whether to use C++ or Python for a largely math-based program. 
Both have great math libraries, but which language is generally faster for complex math?
It all depends if faster is "faster to execute" or "faster to develop". Overall, python will be quicker for development, c++ faster for execution. For working with integers (arithmetic), it has full precision integers, it has a lot of external tools (numpy, pylab...)  My advice would be go python first, if you have performance issue, then switch to cpp (or use external libraries written in cpp from python, in an hybrid approach) 
There is no good answer, it all depends on what you want to do in terms of research / calculus
C++ or Python for an Extensive Math Program?