You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[1-[(5-chloro-2-methoxyphenoxy)methyl]spiro[2.4]heptan-2-yl]benzenesulfonamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24ClNO4S
assistant