Python on android using termux

You can run a python interpreter on android. All you need to install termux on it.
Termux is available on Google play store and F-Droid.

Google play : https://play.google.com/store/apps/details?id=com.termux&hl=en_IN
F-Droid : https://f-droid.org/en/packages/com.termux/
GitHub : https://github.com/termux/termux-app

Installing python 

pkg install python

After installing python you can now install libraries using pip. Python interpreter doesn't have code completion feature which is helpful. Bpython and ptpython are two libraries which can fulfill this requirement. These libraries have other features also. They have features like history which saves your previous code, so you don't have to write a code repeatedly.

Installing bpython

pip install bpython

You can select auto completions  using tab button.

Installing ptpython

pip install ptpython

You can select auto completions using tab, arrow keys.