Bifunctional enzyme that catalyzes the hydrolysis of flavin-mononucleotide (FMN) to riboflavin (vitamin B2) and the phosphorylation of riboflavin to form (FMN) coenzyme. ATP + riboflavin = ADP + FMN + H(+) FMN + H2O = phosphate + riboflavin Optimum pH is acidic (5.5-6.0) for FMN phosphatase activity and basic for riboflavin kinase activity. Optimum temperature is 55 degrees Celsius. Cofactor biosynthesis; FMN biosynthesis; FMN from riboflavin (ATP route): step 1/1. Monomer. In the N-terminal section; belongs to the HAD-like hydrolase superfamily. CbbY/CbbZ/Gph/YieH family. In the C-terminal section; belongs to the flavokinase family.