Members of the Royal Family have wished Archie Harrison Mountbatten-Windsor, son of Prince Harry and Meghan, Duchess of Sussex, a happy birthday as he turns 2 years old.

Archie, who is seventh in line to the throne but does not have an official royal title, has lived in California with the Duke and Duchess of Sussex since they stepped back as senior members of the Royal Family last year.

He was born in England on May 6, 2019, weighing 7 pounds, 3 ounces.

A message shared from the official Royal Family Twitter account on Thursday said: "Wishing Archie Mountbatten-Windsor a very happy 2nd birthday today."

The post included an image of Harry, Meghan and Archie -- who is the Queen's great-grandson -- taken shortly after his birth.

Prince William and Catherine, Duchess of Cambridge, also wished their nephew a happy second birthday on social media.

His grandfather, Charles, the Prince of Wales and Camilla, Duchess of Cornwall, said in a Tweet on Thursday: "Happy birthday to Archie, who turns two today."

Megan revealed earlier this week that she has written a children's book, inspired by Harry and Archie.

Titled "The Bench," the 40-page illustrated book will be released on June 8 and tells the story of a "special bond" shared between a father and son, as viewed through a mother's eyes.

"The Bench started as a poem I wrote for my husband on Father's Day, the month after Archie was born," Meghan said in a statement Tuesday. "That poem became this story."

The book is intended for children aged 3-7.

"My hope is that The Bench resonates with every family, no matter the makeup, as much as it does with mine," she added.

The Duke and Duchess of Sussex announced in February that they were "overjoyed" to be expecting their second child.