There is about a 1 in 45,000 probability that the potentially hazardous asteroid named Apophis will impact Earth in 2036. Based on observations, the asteroid is estimated to have a mass of 2.1 1010 kg, a diameter of 0.25 km, and a density of 2.6 kg/L. It has been estimated that its impact velocity would be 12.6 km/sec. If the mass may be uncertain by a factor of 3 and the impact velocity uncertain by a factor of 2, what is the range of predicted impact energy in joules?