In a Thursday Night Football matchup, the Bengals defeated the Browns 31-10. Browns QB Johnny Manziel made his fourth career start and second of this season in place of the injured Josh McCown.  The Browns received the ball first and punted after gaining only one first down.  The Bengals scored a touchdown on their opening drive to take a 7-0 lead.  The Browns reached the Bengals' 4 yard line, but they were unable to reach the end zone and settled for a field goal.  The Bengals led 7-3 after the first quarter.  The Bengals scored an early second quarter touchdown to go up 14-3.  The Browns went 93 yards and scored a touchdown to cut the deficit to 14-10 heading into halftime. The Bengals dominated the second half as the Browns did not record a first down until the 3 minute mark of the 4th quarter and had only 2 first downs for the entire second half.  The Bengals scored another touchdown to go up 24-10 early in the 4th quarter.  The Browns went 3 and out again, and the Bengals scored another touchdown on their next drive to take a 31-10 lead.  The Browns attempted to respond, but they could not gain a first down and punted again.  The Browns blocked a Bengals' and had the ball at Cincinnati's 37 yard line.  They had two first downs on the drive, but they failed to score a touchdown and turned the ball over on downs, allowing the Bengals to run out the clock.
Question: How many points did the Bengals beat the Browns by?
Answer: 21