The concept of a mole is a unit used in chemistry to express the amount of a substance. One mole of any substance contains Avogadro's number of entities, which is approximately 6.022 × 10^23. These entities can be atoms, molecules, ions, or other particles, depending on the substance.
Therefore, by definition, there is only one atom in one atom. One atom cannot be divided into fractions of itself in the context of counting atoms. However, if you are referring to the number of atoms in a mole of a substance, that would be Avogadro's number (approximately 6.022 × 10^23 atoms) for that particular substance.