You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(2,4-dimethylphenyl)sulfanylmethyl]-1-ethyl-N,N-dimethylbenzimidazole-5-sulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H25N3O2S2
assistant