Bifunctional enzyme which has both oligoribonuclease and pAp-phosphatase activities. Degrades RNA oligonucleotides with a length of 5 nucleotides and shorter, with a preference for 2-mers. Also degrades 24-mers. Converts 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP. adenosine 3',5'-bisphosphate + H2O = AMP + phosphate In accordance with its dual activities, is able to complement both orn and cysQ mutants in E.coli. Was identified as a high-confidence drug target. Belongs to the NrnA oligoribonuclease family.