Hoping to rebound from their season-sweeping loss to the Ravens, the Steelers flew to Paul Brown Stadium for a Week 10 AFC North duel with the Cincinnati Bengals.  Pittsburgh delivered the game's opening punch in the first quarter with quarterback Ben Roethlisberger finding wide receiver Jerricho Cotchery on a 16-yard touchdown pass, followed by a 2-yard touchdown run from running back Rashard Mendenhall.  The Bengals would answer with quarterback Andy Dalton completing a 36-yard touchdown pass to wide receiver A. J. Green.  Cincinnati struck again the second quarter with kicker Mike Nugent getting a 43-yard field goal, yet the Steelers responded with a 39-yard field goal from kicker Shaun Suisham. The Bengals would tie the game in the third quarter with Dalton completing a 1-yard touchdown pass to tight end Jermaine Gresham, yet Pittsburgh came right back with a 9-yard touchdown run from Mendenhall.  Afterwards, the defense would prevent any comeback attempt from Cincinnati. With the win, the Steelers went into their bye week at 7-3.
Question: How many more yards did Andy Dalton gain on touchdown plays compared to Ben Roethlisberger?
Answer: 21