noun
22nd day of the month
Refers specifically to the 22nd calendar day.
会議は２２日に行われます。
The meeting will be held on the 22nd.
noun
22 days
Indicates a duration of 22 days. Often used with counters or in expressions like ２２日間.
このプロジェクトには２２日かかりました。
This project took 22 days.
Compound of 二十二 (にじゅうに, twenty-two) and 日 (にち, day).