An atom of cobalt always has exactly 27 protons. The number of protons in an atom can be found in the upper-left corner of its entry on the periodic table, listed as the element's atomic number. Cobalt's atomic number is 27.
Cobalt also carries 27 electrons. The negative charge of the electrons precisely balances the positive charge of the protons to create a net zero charge for the atom overall. Cobalt is known to have only one stable isotope, cobalt 59. Establishing the number of neutrons in this isotope is as simple as subtracting the 27 protons from its atomic weight of 59 to arrive at 32 neutrons.