It's about nine-tenths as long as a William Henry Harrison's Presidency
In other words, 651.490 hours is 0.8613 times the length of a William Henry Harrison's Presidency, and the length of a William Henry Harrison's Presidency is 1.161 times that amount.(a.k.a. William Henry Harrison, a.k.a. "Tippecanoe," a.k.a. "Old Tippecanoe") (1841)
Having caught pneumonia and pleurisy early in his term as President of the United States, William Henry Harrison died after 756.50 hours minutes in office. Following his death, Congress approved a Presidential widow's pension for Harrison's wife, Anna Symmes, who received a year's worth of Harrison's presidential salary — $25,000 — and the right to free postage for the remainder of her life.
It's about one-and-four-fifths times as long as Boniface VI's reign
In other words, 651.490 hours is 1.8 times the length of Boniface VI's reign, and the length of Boniface VI's reign is 0.56 times that amount.(AD 896)
The Church's enigmatic, shortest-reigning Pope, Boniface VI was pontiff for a period of 360 hours in AD 896 before dying under somewhat mysterious circumstances. His election was subsequently pronounced null by Pope John IX because Boniface had been previously defrocked while serving as a Roman priest.
It's about half as long as The First US Continental Congress
In other words, 651.490 hours is 0.53 times the length of The First US Continental Congress, and the length of The First US Continental Congress is 1.9 times that amount.(1774) (Philadelphia, Pennsylvania)
The First Continental Congress — which included such notable members as Samuel Adams, Thomas Paine, Patrick Henry, John Jay and George Washington — met from September 5th to October 26th, 1774 — a total of 1,200 hours. Of the thirteen original American colonies in existence at the time, only the Province of Georgia sent no delegates to the Congress.
It's about two-fifths as long as The Voyage of the Mayflower
In other words, 651.490 hours is 0.41 times the length of The Voyage of the Mayflower, and the length of The Voyage of the Mayflower is 2.4 times that amount.(1620)
Having left Southampton, England on September 16th (new style), 1620, the Mayflower dropped anchor near Cape Cod, Massachusetts 1,600 hours later on November 21st (new style), 1620. The voyagers had planned to travel in a convoy of two ships, but the smaller Speedwell was found to be leaking (evidently as a result of sabotage) and all passengers had to be moved to the Mayflower instead.
It's about two-fifths as long as Columbus' voyage to America
In other words, 651.490 hours is 0.4 times the length of Columbus' voyage to America, and the length of Columbus' voyage to America is 3 times that amount.(1492) (first voyage)
Attempting to find a western route to Asia, Christopher Columbus set sail on August 3rd, 1492 and landed in the Bahamas on October 12th — 2,000 hours later. After one of Columbus' ships, the Santa Maria ran aground in present-day Haiti, he ordered that the timber be used to used to build a fort and settlement called La Navidad; it remains missing to archaeologists to this day.
It's about three-tenths as long as The First spaceflight (Sputnik)
In other words, 651.490 hours is 0.3 times the length of The First spaceflight (Sputnik), and the length of The First spaceflight (Sputnik) is 3.3 times that amount.(a.k.a. Sputnik 1, a.k.a. Спутник-1, a.k.a. "Satellite-1", a.k.a. Простейший Спутник-1) (1957) (total time in orbit)
Launched from Kazakhstan in 1957, Sputnik was the first artificial satellite placed into orbit around Earth, where it remained for 2,200 hours. During its voyage, it traveled about 70,000,000 km (43,495,983.46 mi), completing an orbit of the planet every 1.60 hours.
It's about three-and-a-half times as long as The Apollo 11 Mission
In other words, 651.490 hours is 3.33568 times the length of The Apollo 11 Mission, and the length of The Apollo 11 Mission is 0.299789 times that amount.(1969) (total mission length)
The first trip by humans to the surface of the Moon, the Apollo 11 Mission began with the launch of the spacecraft from the Kennedy Space Center in Florida on July 16th, 1969 and concluded with the return of the command module on July 24th, 1969 — a total mission time of 195.310 hours. The total time spent by astronauts Neil Armstrong and Edwin "Buzz" Aldrin on the Moon's surface was 2.611110 hours.