About the Number 91 (ninety-one)

Paul Harvey died at the age of 90. MathBabbler already had a nBAB for the number 90, but he didn't have a nBab for the numbers 89 and 91. This nBAB is for the number 91.

   MathBabbler Number Analyst (MBNA) output:
   =========================================
   91 is a natural, whole, integer
   91 is odd
   91 proper divisors are: 1,7,13,
   91 is deficient (sum of divisors is 21)
   91 is happy
   91 is not a Harshad number
   91 is not prime
   91 is undulating
   91 has the prime factors: 7*13
   91 is semiprime (biprime or 2-almost prime)
   91 in octal is 0133
   91 in hexadecimal is 0x5b
   91 in binary is 1011011 (is odious)
   91 nearest square numbers: -10...9 (81...100 [10])
   sqrt(91) = 9.53939
   ln(91) = 4.51086
   log(91) = 1.95904
   91 reciprocal is .01098901098901098901098901098901
   91! is 1.352e+140
   91 is 28.9662 Pi years
   91 is 4 score and 11 years
   91 written as a Roman numeral is XCI

This was the 91st BAB posted during the Spring 2009 BABbling session.

[Wikipedia] 91 is the "smallest positive integer expressible as a sum of two cubes in two different ways if negative roots are allowed: 91 = 6^3+(-5)^3 = 4^3+3^3.

MathBabbler needs to look more closely at the McCarthy 91 function.

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 01 March 2009