61 (number)

From HandWiki
Short description: Natural number
← 60 61 62 →
Divisors1, 61
Greek numeralΞΑ´
Roman numeralLXI
Base 361P36

61 (sixty-one) is the natural number following 60 and preceding 62.

In mathematics

61 is:

  • the 18th prime number.
  • a twin prime with 59.
  • a cuban prime of the form p = x3y3/xy, where x = y + 1.[1]
  • the smallest proper prime, a prime p which ends in the digit 1 in base 10 and whose reciprocal in base 10 has a repeating sequence with length p − 1. In such primes, each digit 0, 1, ..., 9 appears in the repeating sequence the same number of times as does each other digit (namely, p − 1/10 times).[2]:166
  • the exponent of the 9th Mersenne prime.[3] (261 − 1 = 2,305,843,009,213,693,951)
  • the sum of two squares, 52 + 62.
  • a centered square number.[4]
  • a centered hexagonal number.[5]
  • a centered decagonal number.[6]
  • the sixth Euler zigzag number (or Up/down number).
  • a unique prime in base 14, since no other prime has a 6-digit period in base 14.
  • a Pillai prime since 8! + 1 is divisible by 61 but 61 is not one more than a multiple of 8.[7]
  • a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 6, 1, 7, 8, 15, 23, 38, 61...[8]
  • palindromic in bases 6 (1416) and 60 (1160)

In the list of Fortunate numbers, 61 occurs thrice, since adding 61 to either the tenth, twelfth or seventeenth primorial gives a prime number[9] (namely 6,469,693,291; 7,420,738,134,871; and 1,922,760,350,154,212,639,131).

In science


In other fields

See also: List of highways numbered 61

Sixty-one is:

  • The number of the French department Orne
  • The code for international direct dial phone calls to Australia
  • 61*, a 2001 baseball movie directed by Billy Crystal
  • Highway 61 Revisited is a Bob Dylan album
  • The Highway 61 Blues Festival occurs annually in Leland, Mississippi
  • Highway 61 is a 1991 film set on U.S. Route 61
  • U.S. Route 61 is the highway that inspired so much attention on "Highway 61"
  • Part 61 is a law created by the FAA regarding medical exams. This law has often come under attack by AOPA.
  • The P-61 is the Northrop-designed fighter first designated as the XP-61. It first flew on May 26, 1942. It is also known as the Black Widow as it was the first fighter aircraft designed to be a night fighter
  • Sixty 1 is a brand tobacco produced by Nationwide Tobacco
  • 61A is the London address of Margot Wendice (Grace Kelly) and Tony Wendice (Ray Milland) in the movie Dial M for Murder
  • 1 Liberty Place is Philadelphia's tallest building at 61 stories
  • The number of cadets on The Summerall Guards
  • The number of points required to win a "standard" game of cribbage[10]
  • The maximum number of tables that can be joined in a single MariaDB or MySQL query[11]

In sports

  • New York Yankees right fielder Roger Maris hit 61 home runs in 1961, breaking Babe Ruth's single-season record until it was surpassed in 1998 by Mark McGwire and Sammy Sosa.
  • Nolan Ryan and Tom Seaver each had 61 career shutouts
  • Hockey great Wayne Gretzky holds or shares 61 NHL records (40 for regular season, 15 for Stanley Cup playoff, and 6 for All-Star Games)
  • Rotation, a variation of pool, is sometimes called 61
  • Richie Evans' NASCAR Whelen Modified Tour car number was 61 until his death in 1985
  • The number of the laps of the first Formula One night race, Singapore Grand Prix.


  • R. Crandall and C. Pomerance (2005). Prime Numbers: A Computational Perspective. Springer, NY, 2005, p. 79.

External links