Would storing many images in an Android apk file be viable for a social app

I am creating a social app for android and am planning ahead, what would be a viable way in Android to store potentially millions of user generated uploaded photos. I have a MySQL database that saves the image path and was thinking of creating a folder outside of the /drawable directory to save the physical images. I could do that but then I thought that if I did then the Android APK file would just balloon in size since your storing all the images within the app; is there a better way to store many images? I been searching around for answers but there aren't many on this topic for android.