About the Number 691 (six hundred ninety-one)

691 was the MAA (Mathematical Association of America) number of the day on 19 February 2013.

   MathBabbler Number Analyst (MBNA) output:
   =========================================
   691 is a natural, whole, integer
   691 is odd
   691 proper divisors are: 1,
   691 is deficient (sum of divisors is 1)
   691 is unhappy
   691 is a Squarefree Number
   691 is not a Harshad number
   691 is prime
   ...Truman Gerald prime with 661
   ...OEIS:002145 (4n+3; n=164)
   691 is the sum of 13 consecutive primes
   691 = 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79
   691 in octal is 01263
   691 in hexadecimal is 0x2b3
   691 in binary is 1010110011 (is evil)
   691 nearest square numbers: -15...38 (676...729 [27])
   sqrt(691) = 26.2869
   ln(691) = 6.53814
   log(691) = 2.83948
   691 reciprocal is .00144717800289435600578871201157
   691! is 6.32012e+1663
   691 is 219.952 Pi years
   691 is 34 score and 11 years
   691 written as a Roman numeral is DCXCI
   691 = 346^2 - 345^2 and 346 + 345 = 691

The MAA reported that 691 is the "only prime number that is a square when turned upside down (169) and another square when reversed (196).

The MBNA reported that 691 is the sum of 13 consecutive primes and the MAA reported that it is the "smallest prime that can be written as the sum of thirteen consecutive primes."


Creator: Gerald Thurman [gthurman@gmail.com]
Created: 19 February 2013

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