# Mathematica, 42 bytes

    Tr[Times@@@FactorInteger@#]&~FixedPoint~#&

[Try it online!][TIO-j8cws3kg]

(Mathics does not support `Tr`. Use `Tr = Total` in this particular case works)

[Mathics]: http://mathics.github.io/
[TIO-j8cws3kg]: https://tio.run/##y00sychMLv4fUmQbkl@SmGPNlWYL5ESHZOamFjs4OLglJpfkF3nmlaSmpxY5KMeq1bllVqSmBORn5pXUKav9DygCMqKVdRSUFHTtFJR0FNJAihT0HRSqjUx0FAwNdRSMTA1q/wMA "Mathics – Try It Online"