You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[(1S)-1-(1H-benzimidazol-2-yl)ethyl]sulfanyl-N-(5-ethylsulfonyl-2-hydroxyphenyl)acetamide by IUPAC nomenclature, provide its molecular formula.
user
C19H21N3O4S2
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