You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 1-acetyl-N-[2-(N-ethylanilino)ethyl]-2-methyl-2,3-dihydroindole-5-sulfonamide is given. What is its corresponding molecular formula?
user
C21H27N3O3S
assistant