Tennis: PHOTOS: Happy 21st birthday Coco Gauff, captain of 'Tennis Channel Airlines'
NBC Los Angeles: From ‘Congratulations' to Happy Birthday: Post Malone Wishes Fan Happy 21st
In a video posted to TikTok, Nicole Schumacher called Post Malone the "kindest superstar ever" after he wished her son, Andrew Schumacher, a happy 21st birthday. In the video, the Grammy-nominated ...
The Mirror: Happy 21st Birthday, Louis! To celebrate, here's the One Direction singer's best bits, picture special
Happy 21st Birthday, Louis! To celebrate, here's the One Direction singer's best bits, picture special
Bournemouth Daily Echo: Kylie Jenner shares 21st birthday pictures – including hilarious cake topper
Daily Mail: Christie Brinkley wishes daughter Sailor a happy 21st birthday as she shares touching poem and sweet childhood photos
Sailor Brinkley-Cook has taken another trip around the sun. The daughter of Christie Brinkley and Peter Cook celebrated her 21st birthday Tuesday. And her supermodel mom had an extra special happy ...
Christie Brinkley wishes daughter Sailor a happy 21st birthday as she shares touching poem and sweet childhood photos
Liverpool Echo: Celebrate Amadou Onana's 21st birthday with 21 pictures of Everton's big signing
Celebrate Amadou Onana's 21st birthday with 21 pictures of Everton's big signing
Wikipedia and WHO, among others, seem quite happy to write "the 21st century" (with small c), and this the form I prefer. But it's your choice and no-one can criticise you for writing "the twenty-first century".
But the 21st birthday changes a person's legal status. Depending on your country and state, you may be able to [drink, drive, join the army, vote, etc.] two days after that birthday (your "age" is 21), when you could not one week earlier (your "age" was 20).