### About the Number 15 (fifteen)

This nBAB about the number `15` was created in order to complete nBABs for the numbers 10 through 19.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
15 is a natural, whole, integer
15 is odd
15 proper divisors are: 1,3,5,
15 is deficient (sum of divisors is 9)
15 is unhappy
15 is not a Harshad number
15 is not prime
15 is undulating
15 has the prime factors: 3*5
15 is semiprime (biprime or 2-almost prime)
15 in octal is 017
15 in hexadecimal is 0xf
15 in binary is 1111 (is evil)
15 nearest square numbers: -6...1 (9...16 )
sqrt(15) = 3.87298
ln(15) = 2.70805
log(15) = 1.17609
15 reciprocal is .06666666666666666666666666666666
15! is 1.30767e+12
15 is 4.77465 Pi years
15 is 0 score and 15 years
15 written as a Roman numeral is XV
```

MathBabbler posted this nBAB for the number `15` immediately after posting a nBAB for the number 17 and 17 in octal (base-8) equals `15`.

Note to MathBabbler: `15` is a Ruth-Aaron pair when repeated prime factors are counted. {Wikipedia.org::Ruth-Aaron Pair}

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 17 March 2009 