LONDON >> Queen Elizabeth II, who celebrates her 91st birthday today, 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. On September 9, 2015, she became Britain’s longest-reigning monarch, passing her great-great-grandmother Queen Victoria.

— She is the world’s longest-reigning living monarch since the death of Thailand’s King Bhumibol Adulyadej last year.

— She has had 13 British prime ministers serve during her reign, from Winston Churchill to Theresa May.

— 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.

— She has traveled more than 1 million miles (1.6 million kilometers) on official trips, visiting 106 countries.

— She has visited Canada 22 times —the largest number of trips to any nation.

— She has four children, eight grandchildren and five great-grandchildren.

— She has cut back on her official duties in the last few years, but Elizabeth still conducted 332 official engagements in 2016.