The atomic number of Copper is 29.  So immediately we know that there are 29 protons in the nucleus of each Copper atom, and 29 electrons in the cloud surrounding the nucleus of each [neutral] Copper atom.

Copper has two stable isotopes ... ⁶³Copper and ⁶⁵Copper.  So if the Copper atom you're holding in your hand is not radioactive, then it has either (63-29)=34 neutrons or (65-29)=36 neutrons in its nucleus. (There's never a need to round the number of neutrons, because there's no such thing as a part of a neutron.)