Calendar, maps, clock/timer, dictionary. As for learning: Coursera was good years ago, Stepik might be a good site/app too. I haven't tried edX on mobile. Duo

Calendar, maps, clock/timer, dictionary. As for learning: Coursera was good years ago, Stepik might be a good site/app too. I haven't tried edX on mobile. Duolingo to learn languages. Your Youtube feed can be curated to something almost sensible.