It is not safe to save things on coinbase or other exchanges. They can get hacked and you will lose the money you have saved there. It is safer to use a wallet such as freewallet       
https://play.google.com/store/apps/details?id=multi.org.freewallet.app  or coinomi   https://play.google.com/store/apps/details?id=com.coinomi.wallet  or mycelium  https://play.google.com/store/apps/details?id=com.mycelium.wallet