You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 2-[2-(2,3-dihydroxypropoxy)-3-[1-[(2-methylpropan-2-yl)oxy]-3-phenoxypropan-2-yl]oxypropoxy]acetic acid ?
user
C21H34O9
assistant