Catalyzes the reduction of NADP(+) with F420H(2) via hydride transfer, and the reverse reaction, i.e. the reduction of F420 with NADPH. In M.organophilum, an alcohol-fermenting methanogen containing an NADP-dependent alcohol dehydrogenase, is probably involved in the regeneration of F420H(2) required for CO(2) reduction to methane. Thus, during growth on alcohol and CO(2), the F420-dependent NADP reductase probably has the function of coupling the NADP-dependent oxidation of the alcohol to the aldehyde with the F420-dependent reduction of CO(2) to methane. NADP(+) + reduced coenzyme F420-(gamma-L-Glu)(n) = 2 H(+) + NADPH + oxidized coenzyme F420-(gamma-L-Glu)(n) Optimum pH is 5.5 for F420 reduction with NADPH, and 9.2 for NADP(+) reduction with F420H(2). Optimum temperature is 34 degrees Celsius. Homotetramer. Belongs to the F420-dependent NADP reductase family.