41 (forty-one) is the natural number following 40 and preceding 42.

Look up forty-one in Wiktionary, the free dictionary.

• the 13th smallest prime number. The next is 43, making both twin primes.
• the sum of the first six prime numbers (2 + 3 + 5 + 7 + 11 + 13).
• the 12th supersingular prime^[1]
• a Newman–Shanks–Williams prime.^[2]
• the smallest Sophie Germain prime to start a Cunningham chain of the first kind of three terms, {41, 83, 167}.
• an Eisenstein prime, with no imaginary part and real part of the form 3n − 1.
• a Proth prime as it is 5 × 2³ + 1.^[3]
• the largest lucky number of Euler: the polynomial f(k) = k² − k + 41 yields primes for all the integers k with 1 ≤ k < 41.
• the sum of two squares (4² + 5²), which makes it a centered square number.^[4]
• the sum of the first three Mersenne primes, 3, 7, 31.^[5]
• the sum of the sum of the divisors of the first 7 positive integers.
• the smallest integer whose reciprocal has a 5-digit repetend. That is a consequence of the fact that 41 is a factor of 99999.
• the smallest integer whose square root has a continued fraction with period 3.^[6]
• a prime index prime, as 13 is prime.

• The atomic number of niobium.

• "#41", a song by Dave Matthews Band.^[7]
• "American Skin (41 Shots)" is a song by Bruce Springsteen about an immigrant murder victim who was shot at 41 times by the NYPD.^[8]

• The name of an independent documentary about Nicholas O'Neill, the youngest victim of the Station nightclub fire.^[9]
• 2012 documentary on the life of the 41st President of the United States George H. W. Bush.^[10]

• The international direct dialing (IDD) code for Switzerland.^[11]
• Bush 41, George H. W. Bush, the 41st President of the United States.^[12]
• In Mexico "cuarenta y uno" (41) is slang referring to a homosexual. This is due to the 1901 arrest of 41 homosexuals at a hotel in Mexico City during the government of Porfirio Díaz (1876–1911). See: Dance of the Forty-One^[13][14]
• Number of ballistic missile submarines of the George Washington class and its successors, collectively known as the "41 for Freedom".
• The 41st season of CBS's reality program Survivor is simply subtitled Survivor 41.^[15]

• List of highways numbered 41