Prophase is the first stage in mitosis, occurring after the conclusion of the G2 portion of interphase. During prophase, the parent cell chromosomes — which were duplicated during S phase — condense and become thousands of times more compact than they were during interphase.
We know the formula of the density: ρ = ; So the mass will be equal to: m = ρ * V = 2.70 * 21.3 = 57,51 g = 57510 mg of substance. So the answer is 57510.