Catalyzes the hydrolysis of dihydroneopterin triphosphate to dihydroneopterin monophosphate and pyrophosphate. Required for efficient folate biosynthesis. Can also hydrolyze nucleoside triphosphates with a preference for dATP. 7,8-dihydroneopterin 3'-triphosphate + H2O = 7,8-dihydroneopterin 3'-phosphate + diphosphate + H(+) Binds 1 Mg(2+) ion per subunit. Belongs to the Nudix hydrolase family. Extended N-terminus. Extended N-terminus.