Analytic formulas for one-loop contributions to (g−2)_{e,µ} anomalies and decays amplitudes e_b → e_a γ are explicitly derived for the 3-3-1 model with inverse seesaw neutrinos (3-3-1ISS). Using these formulas to investigate Δa_{e,μ} defined as the discrepancies of (g−2)_{e,µ} anomalies between the standard and the 3- 3-1ISS models, our numerical investigations showed that Δa_{e,μ} can reach the maximal values of around 2.5x10^{-14} (1.13x10^{-9}) and 1.4x10^{-14} (0.58x10^{-9})  for normal and inverted order schemes of neutrino oscillation data, respectively. The analytic formulas derived in this work are very useful for estimating dominant contributions to Δa_{e,μ} in new extended versions of the 3-3-1-1ISS model explain successfully the experimental data of (g−2)_{e,µ}.