Catalyzes the phosphate monoester hydrolysis of phytic acid (myo-inositol hexakisphosphate), which results in the stepwise formation of myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates, as well as the liberation of inorganic phosphate. Myo-inositol 2-monophosphate is the end product. Has a broad substrate specificity and is also able to dephosphorylate other classic acid phosphatase substrates such as p-nitrophenyl phosphate, phenyl phosphate, fructose 1,6-bisphosphate, fructose 6-phosphate, glucose 6-phosphate, ribose 5-phosphate, alpha-glycerophosphate, beta-glycerophosphate, 3-phosphoglycerate, phosphoenolpyruvate, as well as ADP and ATP