You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (10bR)-9-chloro-2-phenylspiro[1,10b-dihydropyrazolo[1,5-c][1,3]benzoxazine-5,1'-cyclohexane] is given. What is its corresponding molecular formula?
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C21H21ClN2O
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