Nucleotidase with a broad substrate specificity as it can dephosphorylate various ribo- and deoxyribonucleoside 5'-monophosphates and ribonucleoside 3'-monophosphates with highest affinity to 3'-AMP. Also hydrolyzes polyphosphate (exopolyphosphatase activity) with the preference for short-chain-length substrates (P20-25). Might be involved in the regulation of dNTP and NTP pools, and in the turnover of 3'-mononucleotides produced by numerous intracellular RNases (T1, T2, and F) during the degradation of various RNAs. a ribonucleoside 5'-phosphate + H2O = a ribonucleoside + phosphate a ribonucleoside 3'-phosphate + H2O = a ribonucleoside + phosphate [phosphate](n) + H2O = [phosphate](n-1) + H(+) + phosphate Binds 1 divalent metal cation per subunit. Belongs to the SurE nucleotidase family.