Is a powerful note taking application that supports math (LaTeX), rich markdown, and drawings among other things. The application is free, does not have advertisement or a premium version that it requires users to purchase to get all the functionality it offers.
https://play.google.com/store/apps/details?id=com.appmindlab.nano&hl=en
origin - http://www.pipiscrew.com/2017/07/neutrinote/ neutrinote