By the numbers: Facts and figures about Queen Elizabeth II
Queen Elizabeth II, who celebrates her 91st birthday on Friday, is Britain's oldest-ever monarch and the world's longest-reigning king or queen. Here's a look at some milestones and numbers related to the queen:
Elizabeth has reigned for 65 years and 75 days (as of her birthday on April 21). On September 9, 2015, she became Britain's longest-reigning monarch, passing her great-great-grandmother Queen Victoria.
Queen Elizabeth II is the world's longest-reigning living monarch since the death of Thailand's King Bhumibol Adulyadej last year.
In photo: Queen Elizabeth II, right, and Prince Philip, left, pose with their royal guests, King Bhumibol Adulyadej of Thailand and Queen Sirikit, at Buckingham Palace in London, United Kingdom on July 19, 1960. (AP Photo)
She has had 13 British prime ministers serve during her reign, from Winston Churchill to Theresa May.
In photo: At left, a Nov. 24, 1954 file photo showing Elizabeth II of England and Prime Minister, Sir Winston Churchill at Waterloo station. In front, Prince Charles and Princess Anne. At right, British Prime Minister Theresa May with Queen Elizabeth II. (AP photos)
She has met 12 U.S. presidents, from Herbert Hoover (after he left office) to Barack Obama, more than a quarter of all the U.S. presidents since Independence. She is due to host President Donald Trump for a state visit later this year.
In photo: Queen Elizabeth II is flanked by former President Herbert Hoover, left, and New York City's Mayor Robert Wagner at luncheon in the hotel Waldorf-Astoria, New York on Oct. 21, 1957. (AP Photo)
She has four children, eight grandchildren and five great-grandchildren.
In photo: Queen Elizabeth II walks with her family on April 19,1965 at Frogmore, Windsor, England. Prince Edward, 1, is in pram with Prince Andrew, 4, holding on. Prince Philip and their two eldest children, Princess Anne and Prince Charles, the heir apparent, complete the family group. (AP Photo)
She has cut back on her official duties in the last few years, but Elizabeth still conducted 332 official engagements in 2016.
In photo: Britain's Queen Elizabeth II makes a speech as Colombia's president Juan Manuel Santos, left, listens during a state banquet at Buckingham Palace in London, Tuesday Nov. 1, 2016. (Dominic Lipinski/Pool via AP)