The energy spectra of the Hamiltonian of a single electron confined in a parabolic quantum dot (QD) have been investigated, taking into consideration different external effects such as the Rashba spin-orbit interaction term, applied uniform magnetic field, and topological defect. The results show that the topological defect enhances the energy levels, while the increment in the strength of the Rashba parameter removes the spin degeneracy and reduces the energy levels. The obtained QD energy spectra are used to study the statistical mean energy from which we consider the behavior of the magnetization and magnetic susceptibility on the QD. It is found that the topological defects and Rashba terms play important roles in flipping the sign of the magnetic susceptibility from negative(χ<0) to positive sign (χ>0). The present results are in very good qualitative agreement compared with the reported ones.