You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-1-(7-hydroxy-5-methoxy-2,2-dimethylchromen-8-yl)-3-(4-hydroxyphenyl)prop-2-en-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20O5
assistant