You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (10S,15R)-7-(3-chloro-2-methylphenyl)-1,12-diazatetracyclo[7.6.1.05,16.010,15]hexadeca-5(16),6,8-triene by IUPAC nomenclature, provide its molecular formula.
user
C21H23ClN2
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