You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2S)-N-[2-[(4-chlorophenyl)methylsulfanyl]ethyl]-2-(2,3,5-trimethylphenoxy)propanamide by IUPAC nomenclature, provide its molecular formula.
user
C21H26ClNO2S
assistant