September 21 Holidays, events and History 2021.
| Date | Day | Holiday Name | Holiday Type | Country |
| 21 Sep | Tuesday | Kwame Nkrumah Memorial Day | Public Holiday | Ghana |
| Sep 21 | Tuesday | Day after mid Autumn Festival | National Holiday | Hong Kong |
| Sep 21 | Tuesday | Harvest Festival | National Holiday | South Korea |
| 21 Sep | Tuesday | Mid-Autumn Festival | National holiday | Taiwan |
| 21 Sep | Tuesday | Independence Day | National holiday | Malta |
| 21 Sep | Tuesday | St. Matthew’s Day | Municipal Holiday | Portuagal |
| 21 Sep | Tuesday | Independence Day | National holiday | Armenia |
| 21 Sep | Tuesday | Sukkot (Day 1) | National holiday, Hebrew | Israel |