127 (number)

← 126 127 128 →
← 120 121 122 123 124 125 126 127 128 129 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	one hundred twenty-seven
Ordinal	127th (one hundred and twenty-seventh)
Factorization	prime
Prime	31st
Divisors	1, 127
Roman numeral	CXXVII
Binary	11111112
Ternary	112013
Quaternary	13334
Quinary	10025
Senary	3316
Octal	1778
Duodecimal	A712
Hexadecimal	7F16
Vigesimal	6720
Base 36	3J36

127 (one hundred [and] twenty-seven) is the natural number following 126 and preceding 128. It is also a prime number.

In mathematics

• As a Mersenne prime, 127 is related to the perfect number 8128. 127 is also an exponent for another Mersenne prime 2¹²⁷ - 1, which was discovered by Édouard Lucas in 1876, and held the record for the largest known prime for 75 years - it is still the largest prime ever discovered by hand calculations. Furthermore, 127 is equal to 2⁷ - 1, and 7 is equal to 2³ - 1, and 3 is the smallest Mersenne prime, this makes 7 the smallest double Mersenne prime and 127 the smallest triple Mersenne prime.
• 127 is also a cuban prime of the form $p=(x^{3}-y^{3})/(x-y)$, $x=y+1$.^[1] The next prime is 131, with which it comprises a cousin prime. Because the next odd number, 129, is a semiprime, 127 is a Chen prime. 127 is greater than the arithmetic mean of its two neighboring primes, thus it is a strong prime.^[2]
• 127 is a centered hexagonal number.^[3]
• It is the 7th Motzkin number.^[4]
• 127 is a palindromic prime in nonary and binary.
• It is the first nice Friedman number in base 10, since 127 = -1 + 2⁷, as well as binary since 1111111 = (1 + 1)¹¹¹ - 1 * 1.
• 127 is the sum of the sums of the divisors of the first 12 positive integers.^[5]
• 127 is the smallest prime that can be written as the sum of 9 regular primes, 127 = 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29.^[6]
• 127 is the smallest odd number that can't be written in the form p + 2^x for p=prime number and x=integer, since 127 - 2⁰ = 126, 127 - 2¹ = 125, 127 - 2² = 123, 127 - 2³ = 119, 127 - 2⁴ = 111, 127 - 2⁵ = 95, and 127 - 2⁶ = 63 are all composite numbers.^[7]
• 127 is an isolated prime where both p-2 and p+2 isn't prime.

In the military

• USNS Mission San Luis Obispo (T-AO-127) was a Mission Buenaventura Class fleet oilers during World War II
• USS Admiral W. S. Sims (AP-127) was a United States Navy transport ship
• USS Allendale (APA-127) was a United States Navy Haskell-class attack transport ship
• USS Alnitah (AK-127) was a United States Navy Crater-class cargo ship in World War II
• USS Raccoon (IX-127), was a United States Navy Armadillo-class tanker
• USS Tumult (AM-127) was a United States Navy Auk-class minesweeper for removing mines from minefields

In religion

• The biblical figure Sarah died at the age of 127.^[8]
• According to the Book of Esther 1:1, the Persian Empire under Ahasuerus contained 127 provinces

In transportation

• The small Fiat 127 automobile
• London Buses route 127 is a Transport for London contracted bus route in London
• 127 is the number of many roads, including U.S. Route 127
• STS-127 was a Space Shuttle Endeavour mission to the International Space Station which launched on June 15, 2009

In other fields

127 is also:

• 127 Hours is a film released in 2010
• The year AD 127 or 127 BC
• 127 AH is a year in the Islamic calendar that corresponds to 744 – 745 CE
• 127 Johanna, a Main belt asteroid
• 127 film, a film format
• The atomic number of Unbiseptium, an element that has not yet been discovered
• The LZ 127 Graf Zeppelin, a dirigible
• Sonnet 127 by William Shakespeare
• 127th Street Ensemble was a troupe of African-American actors which included Tupac Amaru Shakur
• In IP (Internet Protocol) Version 4, it is the last Class A network and is also the subnet used for loopback functionality in computer networking
• The highest signed 8 bit integer
• The non-printable "Delete" (DEL) control character in ASCII.

See also

• 127th (disambiguation)
• List of highways numbered 127
• United Nations Security Council Resolution 127

References

1. "Sloane's A002407 : Cuban primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
2. "Sloane's A051634 : Strong primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
3. "Sloane's A003215 : Hex (or centered hexagonal) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
4. "Sloane's A001006 : Motzkin numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
5. "Sloane's A024916 : sum_{k=1..n} sigma(k) where sigma(n) = sum of divisors of n". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. "Sloane's A071148". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
7. "Sloane's A006285". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
8. "Sara". Catholic Encyclopedia. Retrieved September 8, 2015.

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 136 - 138