Question

what is the density of black hole

Answer 1

Stellar black hole: mass = 2× 1031 kg, volume = 3.4× 1012 m3 . The density would then be mass/volume, or 6×1018 kg/m3 . Galactic sized: Mass is 2× 1039 kg, volume= 1037 m3 , density= 200 kg/m3 . It seems that the larger they are, the less dense they would be, but only if you consider the event horizon as the limit.