Dephosphorylates several organic phosphate monoesters including 5'-AMP, 3'-AMP, pNPP, PDP, 5'-UMP, 3'-UMP, G2P, glucose 6-P and ribose 5-P. No activity toward organic phosphate diesters. Also has a phosphotransferase activity catalyzing the transfer of low-energy phosphate groups from organic phosphate monoesters to free hydroxyl groups of various organic compounds. a phosphate monoester + H2O = an alcohol + phosphate Binds 1 Mg(2+) ion per subunit. Activated by ethanol. Also activated by Co(2+), Zn(2+) and glycerol. Inhibited by EDTA, inorganic phosphate, nucleosides and Ca(2+). Unaffected by fluoride and tartrate. Optimum pH is about 6 using pNPP as substrate. Retains more than 50% of maximal activity in the pH range 4-7. Homotetramer. Belongs to the class B bacterial acid phosphatase family.