Properties of nuclei
The density inside a large nucleus is approximately 1.4 E44 nucleons per cubic meter. The radius of a nucleus is proportional to the cubic root of the number of particles,
From our studies of atomic physics, we saw that the radius of the innermost Bohr orbit around a nucleus of charge Z was (5.3 E-11 m)/Z. So for the heaviest nucleus the radius of the inner-most electronic orbit is 100 times larger than the radius of the nucleus.
Due to the Pauli-exclusion principle which discourages like particles from being in the same place, nuclei prefer configurations of roughly equal numbers of protons and neutrons. However, due to the Coulomb force, heavy nuclei prefer to have more neutrons than protons. For example 238U has 146 neutrons and only 92 protons.