Flight Changi Airport departs from Singapore Changi Airport at 23:15 and arrives at Mumbai Chhatrapati Shivaji International Airport at 02:15.
The flighttime is about 5h 30m. The distance travelled ("as the bird flies"): 3418 Km. So the average speed is roughly 621 Km.
There is an 2.5 hour time difference between Singapore and Mumbai