You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2,2-dioxo-3,4-dihydro-[1,2,4]thiadiazino[3,4-b][1,3]benzothiazol-8-yl)-[4-(2-hydroxybenzoyl)piperazin-1-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20N4O5S2
assistant