A little bit jank, but there is also a port for android available[0]. It still has SI prefixes and unit conversion, but you need to have a good keyboard to really take advantage of it.
[0] https://github.com/mikkosyrja/speedcrunch-android
On Android, so far, I prefer Calculator++ - it supports complex numbers (not that I need those, but sqrt(-1) returns i) and has fairly capable graphing.