129 (number) explained

Number:	129
Divisor:	1, 3, 43, 129

129 (one hundred [and] twenty-nine) is the natural number following 128 and preceding 130.

In mathematics

129 is the sum of the first ten prime numbers. It is the smallest number that can be expressed as a sum of three squares in four different ways:

11 ^{2+2} ^{2+2} ^{2} , 10 ^{2+5} ^{2+2} ^{2} , 8 ^{2+8} ^{2+1} ^{2} , and 8 ^{2+7} ^{2+4} ^{2} .

129 is the product of only two primes, 3 and 43, making 129 a semiprime. Since 3 and 43 are both Gaussian primes, this means that 129 is a Blum integer.^[1]

129 is a repdigit in base 6 (333).

129 is a happy number.^[2]

129 is a centered octahedral number.^[3]

In the military

• Raytheon AGM-129 ACM (Advanced Cruise Missile) was a low observable, sub-sonic, jet-powered, air-launched cruise missile used by the United States Air Force
• Soviet submarine K-129 (1960) was a Soviet Pacific Fleet nuclear submarine that sank in 1968
• was a United States Navy Mission Buenaventura-class fleet oilers during World War II
• was a Crosley-class high speed transport of the United States Navy
• was the lead ship of her class of destroyer escort in the United States Navy
• was a United States Navy Haskell-class attack transport during World War II
• was a United States Navy Crater-class cargo ship during World War II
• was a United States Navy Auk-class minesweeper for removing naval mines laid in the water
• Agusta A129 Mangusta is an attack helicopter originally designed and produced by Italian company Agusta
• The 129th Rescue Wing (129 RQW) is a unit of the California Air National Guard

In transportation

• LZ 129 Hindenburg was a German zeppelin which went up in flames while landing on May 6, 1937
• London Buses route 129 is a Transport for London contracted bus route in London
• STS-129 was a Space Shuttle mission to the International Space Station, flown in November 2009 by the shuttle Atlantis.

In other fields

129 is also:

• The year AD 129 or 129 BC
• 129 AH is a year in the Islamic calendar that corresponds to 746 - 747 CE
• 129 Antigone is a main belt asteroid
• The atomic number of unbiennium, an element yet to be discovered
• A film format: 129 film
• Sonnet 129 by William Shakespeare

See also

• List of highways numbered 129
• United Nations Security Council Resolution 129

Notes and References

1. Web site: Sloane's A016105 : Blum integers. The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-05-27.
2. Web site: Sloane's A007770 : Happy numbers. The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-05-27.
3. 2022-06-02.