You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 7-[(4R,5R)-4-hydroxy-5-[(E,3S)-3-hydroxyoct-1-enyl]-2-methylcyclopenten-1-yl]heptanoic acid by IUPAC nomenclature, provide its molecular formula.
user
C21H36O4
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