You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 2-[[1-(2,6-dichlorophenyl)-5-(2-methylpropyl)pyrazol-3-yl]methyl]-3H-1,2-benzothiazole 1,1-dioxide into its molecular formula.
user
C21H21Cl2N3O2S
assistant