The black hole bit is the majority of the problem.

The density needed to become a black hole goes down as the radius of object increases. For the planet that you're talking about, if it had a density of 0.00000001488 g/cm^3, it would collapse into a black hole. The density of the earth is around 5.51 g/cm^3.

You would need this planet to be something like a shell of unobtanium, or a lot of antigravity devices to stop from collapsing.

The black hole bit is the majority of the problem.

The density needed to become a black hole goes down as the radius of object increases. For the planet that you're talking about, if it had a density of $0.00000001488~\frac{\text{g}}{\text{cm}^{3}}$, it would collapse into a black hole. The density of the Earth is around $5.51~\frac{\text{g}}{\text{cm}^{3}}$.

You would need this planet to be something like a shell of unobtanium, or a lot of antigravity devices to stop from collapsing.