You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 3-cycloheptyl-1-(2,4-dichlorophenyl)-7,8-dimethyl-2,4-dihydropyrimido[1,2-a][1,3,5]triazin-6-one .
user
C21H26Cl2N4O
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