You’re clearly not Muslim. You can simply ask me to clarify the purpose of these apps 
Azan apps send a notification when it’s (and around) prayer time five times a day. This is especially useful for Muslim in non-Muslim majority countries where there’s no outloud call for prayer in the streets. It also has so many other useful features like prayer litanies, Lunar calendar and Islamic holy days notifications, etc. It also helps with the Qibla.
Qur’an and Athkar apps also are very useful for many people as they suggest and notify or keep a database of athkar/verses suitable for times/context/locations, etc.