You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1,3,5-trimethyl-N-[2-(4-phenylpiperazin-1-yl)pyrimidin-5-yl]pyrazole-4-carboxamide by IUPAC nomenclature, provide its molecular formula.
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C21H25N7O
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