The nucleus of a neutral potassium atom is "surrounded" by

19 electrons

Explanation:

An atom is smallest unit of a matter or substance.It consist of three subatomic particles : electrons, protons, neutrons.

Protons and neutrons are located in the center of an atom where mass of an atom is concentrated.  Electrons are located outside the nucleus where they orbit in different energy levels around the nucleus.

Potassium is an element with atomic number of 19 and thus contains 19 electrons.The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration

Total number of electrons = 2+2+6+2+6+1 = 19