You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(2-methylpropyl)-1,1-dioxospiro[3,5-dihydro-6,1lambda6,2-benzoxathiazocine-4,4'-piperidine]-1'-yl]-(1H-pyrazol-5-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H28N4O4S
assistant