According to the royal family's website, when male or unmarried female descendants of Queen Elizabeth need to use a surname (which is what Americans would more often refer to as a last name), Mountbatten-Windsor is available to them. It's unclear why the statement regarding Andrew listed the name without a hyphen.

Buckingham Palace has announced Prince Andrew will lose his royal titles and honours. But where does his surname Mountbatten Windsor come from?

Connections to the Royal Family are very close, with Prince Phillip's mother being Princess Alice of Battenberg and Lord Mountbatten playing a key role in the current king's life. The name Mountbatten-Windsor was created in the 1960s, combining both Queen Elizabeth II and Prince Philip's surnames.

Where does Andrew’s new name come from? - The King has begun the formal process to strip the titles from Prince Andrew

The Mountbattens are a very powerful British family known for their strong connection to the Royal Family. The name Mountbatten is the anglicised version of the German surname Battenberg, with the name being changed during the First World War.

Andrew Mountbatten Windsor, formerly known as Prince Andrew, reportedly had another great love before Sarah “Fergie” Ferguson. The former Duke of York, whose royal titles were stripped by King Charles III on Thursday,