You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-1-(2-ethyl-3-methylbenzimidazol-3-ium-1-yl)-3-(4-propan-2-ylphenoxy)propan-2-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H29N2O2+
assistant