By analyzing the R values measured at 68 energy points in the energy region between 3.650 and 3.872 GeV reported in our previous paper, we have precisely measured the mass, the total width and the leptonic width of the psi (3770) resonance to be M-psi (3770) = 3772.4 +/- 0.4 +/- 0.3 MeV, Gamma(tot)(psi(3770)) = 28.5 +/- 1.2 +/- 0.2 MeV and Gamma(ee)(psi(3770)) = 277 +/- 11 +/- 13 eV, respectively. We have measured the leptonic branching fraction of the psi (3770) of the psi (3770) production cross section at its peak to be B[psi (3770) -> e(+) e(-)] = (0.97 +/- 0.03 +/- 0.05) x 10(-5) and sigm...