I cun dey reason say, If na so e be for BVN and some kind other numbers dem wey people dey save for phone, e mean say some kind people wey dey use bitcoins dey fit dey also save their keys for "Notes" or save screenshot of am for their phone gallery. It is not save at all ooo...MAke we nor follow dey go make that mistake oooo, Do not save your private keys on your phone either for Notes or for Gallery. Crimanals dey smart well well, you need to get sense too to follow dem up.
I think important information shouldn't be stored on the phone because if peradventure you lose your phone there are tendency that some personal information you store on your phone might be exposed thereby your personal information might be tempered with. I suggest instead of storing your personal information on your phone, you rather use your email and you can still access the information even when you phone is stolen through your email so instead of storing your information on your phone, email is preferable.