You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 1-[5-methyl-2-(4-methylphenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]piperidine-4-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25N5O2
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