You are playing golf with a friend on a scenic course in the Rocky Mountains near Denver. When your friend misses an easy putt, he blames it on not taking into account the gravitational attraction of a nearby mountain on the ball. Suppose the golf ball has a mass of 46 g, and you guess that the center of the mountain is 670.3 meters away and has a total mass of 109 kg. How big was the force? Express your answer in nano-newtons (billionths of a newton).