Hydrolyzes homoallylic isopentenyl diphosphate (IPP), its allylic isomer dimethylallyl diphosphate (DMAPP) and short-chain prenyl diphosphates geranyl diphosphate (GPP) and farnesyl diphosphate (FPP) to their corresponding monophosphate forms with high activity. The preferred substrate is IPP. ADP, NADPH, Ap5A and thiamine diphosphate (TPP) are weakly hydrolyzed. No hydrolysis with ATP, dNTPs, 8-OH-dGTP, NAD+, FAD or acetyl-CoA. The likely physiological role of this enzyme is to provide a substrate dimethylallyl phosphate (DMAP) for prenylated flavin mononucleotide (prenyl-FMN) synthase MM_1871 involved in the biosynthesis of prenyl-FMN, a coenzyme required in the archaea-specific mevalonate pathway. dimethylallyl diphosphate + H2O = dimethylallyl phosphate + H(+) + phosphate H2O + isopentenyl diphosphate = H(+) + isopentenyl phosphate + phosphate (2E,6E)-farnesyl diphosphate + H2O = (2E,6E)-farnesyl phosphate + H(+) + phosphate (2E)-geranyl diphosphate + H2O = (2E)-geranyl phosphate + H(+) + phosphate kcat is 0.139 sec(-1) with DMAPP as substrate. kcat is 0.681 sec(-1) with as IPP substrate. kcat is 0.395 sec(-1) with GPP as substrate. kcat is 0.298 sec(-1) with FPP as substrate. Optimum pH is 8.5. Optimum temperature is 37 degrees Celsius. Stable at 30 degrees Celsius. More than half of its activity is lost after 30 min of treatment at 35 degrees Celsius. Activity is lost by 30 min of treatment above 40 degrees Celsius. Isoprenoid biosynthesis. Belongs to the Nudix hydrolase family.