Gallium is a metal with a wide variety of uses. A few of its applications include computer memory chips, light emitting diodes as well as lasers. Radioactive isotopes of gallium are utilized to image the human body and locate tumors. Naturally taking place gallium consists of two isotopes.
One of those isotopes is 71Ga with an isotopic mass of 70.9247050amu as well as an abundance of 39.892%. Explain what is the mass number of the other isotope?