You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-[2-(cyclohexen-1-yl)ethylamino]-6-methylpyrimidin-4-yl]-(4-ethylpiperazin-1-yl)methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H31N5O
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