You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-(4-chloro-2-methoxyphenyl)-2-(phenoxymethyl)-1,8a-dihydroimidazo[1,2-a]pyrimidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18ClN3O2
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