Some do this in 8 days
https://en.wikipedia.org/wiki/Race_Across_America
But 51 days is also fantastic!
Completely different experience though, since RAAM is a supported race, a very different kind of suffering. The Trans Am is a more comparable one (though still a race): https://en.wikipedia.org/wiki/Trans_Am_Bike_Race
Your brother learned to read at the age of 4, but learning it at 7 1/2 is also fantastic!