You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(6R)-20-amino-9-fluoro-8-methyl-2,11,17,21,22,25-hexazapentacyclo[17.5.2.02,6.07,12.022,26]hexacosa-1(25),9,11,19(26),20,23-hexaen-18-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26FN7O
assistant