That's an obviously too low figure, but the "1 million US dead" figure from an invasion is equally bogus.
I think the history or military channel had a very good analysis of this and I believe their best estimate is around 300,000 to 400,000 American casualties and 2 million plus Japanese casualitied. I actually believe it would have been more given that the Japanese military planners fortified all the southern beaches exactly where our military planners had decided the beach heads would be established and the routes north through the main small southern island of Japan. The Japanese were no dummies, they looked at it from the perspective of where would I invade if we were them (the Americans). Again, when our military people went through this area after the war, they were amazed at the level of prepareness that the Japanese had put into homeland defense and knew for sure that the two atomic bombs saved more of their and our lives than they killed.