About the Number 689 (six hundred eighty-nine)

@MathBabbler received the following tweet from @MAAnow on 2013.12.11.

	Today's number is 689 http://bit.ly/J4wTap

Hmm... From the MAA posting: "689 is the smallest strobogrammatic brilliant number. Deleting the middle digit gives the smallest strobogrammatic semiprime (69)."

MathBabbler Number Analyst (MBNA) output:
=========================================
689 is a natural, whole, integer
689 is odd
689 proper divisors are: 1,13,53,
689 has 3 proper divisors
689 is deficient (sum of divisors is 67; ratio: 0.0972424)
689 is unhappy
689 is a Squarefree Number
689 is not a Harshad number
689 is not prime
689 has the prime factors: 13*53 (sum=66)
689 is semiprime (biprime or 2-almost prime)
13...53...answer: 66
689 is the sum of 7 consecutive primes
689 = 83 + 89 + 97 + 101 + 103 + 107 + 109
689 in octal is 01261
689 in hexadecimal is 0x2b1
689 in binary is 1010110001 (is odious)
689 nearest square numbers: -13...40 (676...729 [27])
sqrt(689) = 26.2488
ln(689) = 6.53524
log(689) = 2.83822
689 reciprocal is .00145137880986937590711175616835
689! is 1.32556e+1658
689 is 219.316 Pi years
689 is 34 score and 9 years
689 written as a Roman numeral is DCLXXXIX
689 = 345^2 - 344^2 and 345 + 344 = 689

log8(689) = 3.14279, which when rounded to the nearest hundredth (3.14) equals Pi rounded to the nearest hundredth.

Update::2015.12.02

FindTheFactors.com::What Makes 689 Amazing?


Creator: Gerald Thurman [gthurman@gmail.com]
Created: 11 December 2013

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