Catalyzes the hydrolysis of the N-glycosidic bond of AMP to form adenine and ribose 5-phosphate. Involved in regulation of AMP concentrations. AMP + H2O = adenine + D-ribose 5-phosphate Allosterically activated by Mg-ATP. Inhibited by inorganic phosphate and formycin monophosphate. Homohexamer. Trimer of dimers. By cAMP at limiting phosphate concentrations. Repressed by phosphate. Each monomer consists of two domains: a C-terminal catalytic domain and a putative N-terminal regulatory domain. Knockout elevates intracellular ATP levels and increases cold tolerance. AMP nucleosidase binds AMP at the catalytic site, Mg-ATP at an allosteric regulatory site, and inorganic phosphate also at a regulatory site. Belongs to the AMP nucleosidase family.