`received the following tweet from`

@MathBabbler`on`

@MAAnow`2010.03.01`

.Today's Number: 991 http://cot.ag/9bnoi7MathBabbler Number Analyst (MBNA) output: ========================================= 991 is a natural, whole, integer 991 is odd 991 proper divisors are: 1, 991 is deficient (sum of divisors is 1) 991 is unhappy 991 is not a Harshad number 991 is prime ...Sexy prime with 997 ...OEIS:002145 (4n+3; n=247) ...Super 991 is a lucky number 991 is the sum of 7 consecutive primes 991 = 127 + 131 + 137 + 139 + 149 + 151 + 157 991 in octal is 01737 991 in hexadecimal is 0x3df 991 in binary is 1111011111 (is odious) 991 nearest square numbers: -30...33 (961...1024 [32]) sqrt(991) = 31.4802 ln(991) = 6.89871 log(991) = 2.99607 991 reciprocal is .00100908173562058526740665993945 991! is 4.1718e+2540 991 is 315.445 Pi years 991 is 49 score and 11 years 991 written as a Roman numeral is CMXCI 991 = 496^2 - 495^2 and 496 + 495 = 991The MAA's NumberADay indicated that

`is the "largest three-digit permutable prime. In other words, 991, 919, and 199 are all primes."`

991

**Creator:** Gerald Thurman
[gthurman@gmail.com]

**Created:** 01 March 2010

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