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 M^{3}. Since the Schwartzschild radius R is proportional to M, the life expectancy of a black hole can also be expressed as being proportional to R^{3}, 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.)