Wake me up in 21 hours 28 minutes. Set timer for 21 hours 28 minutes. Set the alarm for 21 hours 28 minutes from now. It is a free and easy-to-use countdown timer.
Set this 21 hours 28 minutes timer and let the countdown start. Use it to control the time limit of any activity and be notified when that limit has been reached. When the countdown stops, an alarm sound will ring.
Start 21 hours 28 minutes timer.