One very interesting fact about Hawking radiation is that it leads to the evaporation of a black hole of mass M in a time proportional to M3. Since the Schwartzschild radius R is proportional to M, the life expectancy of a black hole can also be expressed as being proportional to R3, or, proportional to the volume of the black hole. (All of this assuming, of course, that the black hole doesn't eat anything more in the process of evaporating.)