This cannot be answered properly without knowing what your speed is.
1 hour 21 minutes @65 mph
21 minutes.
Approximately 20 minutes.
21 minutes, 13.85 seconds
It would take .525 of an hour to drive 21 miles at 40mph without traffic, or a little over half an hour.
21 hours 40 minutes.
1300 miles, 21 hours
1 hour 21 minutes.
.42 hours
38 minutes 11 seconds.
10 hours 21 minutes.
22 minutes 54.5 seconds.