Usage patterns
〈時〉の二十日the 20th of (a given month)
There is a meeting on the 20th of this month.
〈事〉に二十日かかるto take twenty days (to do something)
It took twenty days to finish this construction work.
二十日ぶりに〈動詞〉to do something for the first time in twenty days
It rained for the first time in twenty days.