(2 * G / c^2) * (mass of Uranus)

The Schwarzschild radius is a characteristic radius associated with any mass, at which the escape velocity for the mass is exactly equal to the speed of light. Basically, if an object of mass m is compressed to fit inside it's Schwarzschild radius, it'll become a black hole.

You may be further excited by the knowledge that the Schwarzschild radius of the Sun is about 3 centimeters, or a distance slightly smaller than the length of your pinkie finger.

This means that, if you happen to own a really zippy car, something that can travel at the speed of light, say, you're pretty much safe outside that 3cm distance. If you have something slightly more realistic, like a 1976 Ford Fiesta, you'll probably want to be at least 3 kilometers from the Sun when it finally collapses.

And make sure you use your high-beams, because it'll be pretty dark.

This absolutely useless piece of totally impractical trivia was brought to you by today's discovery of a bunch of holes. Way to justify that funding, NASA!