A star of mass 2.0 x 1031 kg that is 4.4 x 1020 m from the center of a galaxy revolves around that center once every 2.6 x 108 years. Assuming that this star is essentially at the edge of the galaxy, each of the stars in the galaxy has a mass equal to that of this star, and the stars are distributed uniformly in a sphere about the galactic center, estimate the number of stars in the galaxy. (Do not round your answer to an order of magnitude.)