You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2-[4-(2,6-dichlorophenyl)sulfonylpiperazin-1-yl]-1-(2-methyl-2,3-dihydroindol-1-yl)ethanone .
user
C21H23Cl2N3O3S
assistant