In an atom, protons and electrons are held close together, but the compactness of the nucleus is on a whole different level. If you think about the kind of forces it takes to keep those positively charged particles packed in the nucleus, the force must be absolutely tremendous, remember that it goes by the square of the distance

That is the nuclear force. The force of the nucleus. It is on a whole different level of magnitude to the electrical forces you know from day-to-day life.
The nuclear force is so powerful that even a very small number of reactions can result in an immense detonation.