And puts some hard, theoretical limits on using black holes as total conversion reactors. Reducing the power output to a terawatt requires 2x10^10kg... Probably not practical. (It would also have a radius of 0.03 femtometers. A proton? ~0.84)
The mass of the smallest-possible black hole is called the Planck Mass (~21 micrograms). Such a black hole would have a Schwarzschild radius of 1 planck length, and would evaporate in 1 planck time. The planck mass is also considered to be the largest-possible mass of an elementary particle.
