Density functional theory calculations on medium-sized GanAsm clusters (n + m = 17-24, n - m = 0, +/- 1) are reported. The total polarizabilities of GanAsm clusters exhibit a linear dependence on their volumes despite of different composition, giving a way to predict the polarizabilities of larger clusters. The polarizabilities are also strongly correlated to ionization potentials and composition. Isomerization may be the main reason why the even-odd oscillation of polarizabilities disappears in this size from experiment. Ultra stability of Ga9As10 and unusual electronic properties of Ga10As11 are found due to their special structures. (C) 2011 Elsevier B.V. All rights reserved.