You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5,6-dimethyl-N-[2-(4-phenylsulfanylphenoxy)ethyl]-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine The above is the IUPAC name of a molecule. Write its molecular formula.
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C21H21N5OS
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