US President Joe Biden turned 82 on Wednesday, an age no sitting US president has ever reached.

The president had no public events on his schedule yesterday, after returning from a trip to South America late Tuesday night.

His family, friends and colleagues, including first lady Jill Biden and former President Barack Obama, celebrated Biden on social media.

“Happy Birthday to my dear friend and our amazing President Joe Biden,” Vice President Kamala Harris wrote on Instagram.

Biden dropped out of the presidential race in July after some voters thought he was too old for the job, and raised questions about his mental fitness after his poor debate performance against Republican Donald Trump in June.

Trump, 78, defeated Democratic candidate Kamala Harris, 60, in the Nov. 5 election, and Trump could surpass Biden's age record in his next term, as he will be 82 years and 7 months old when the next presidential transition takes place in 2029.

The previous record for oldest serving president was held by Republican Ronald Reagan, who completed his second four-year term at the age of 77.