About the Number 19 (nineteen)

19 January 2009 was Martin Luther King, Jr. Day.

   MathBabbler Number Analyst (MBNA) output:
   =========================================
   19 is a natural, whole, integer
   19 is odd
   19 proper divisors are: 1,
   19 is deficient (sum of divisors is 1)
   19 is happy
   19 is not a Harshad number
   19 is prime
   ...Cousin prime with 23
   ...Sexy prime with 13
   ...Twin prime with 17
   ...OEIS:002145 (4n+3; n=4)
   ...prime triplet {13, 17, 19}
   ...prime triplet {17, 19, 23}
   ...prime quadruplet {11, 13, 17, 19}
   19 is undulating
   19 in octal is 023
   19 in hexadecimal is 0x13
   19 in binary is 10011 (is odious)
   19 nearest square numbers: -3...6 (16...25 [5])
   sqrt(19) = 4.3589
   ln(19) = 2.94444
   log(19) = 1.27875
   19 reciprocal is .05263157894736842105263157894736
   19! is 1.21645e+17
   19 is 6.04789 Pi years
   19 is 0 score and 19 years
   19 written as a Roman numeral is XIX

19 is the last year a teenager is a teenager (at least numerically).

19 is 13 in base-16. [And 13 is the first year a teenager is a teenager.]

Update::2014.06.04

BAB::19th Amendment Passed By Congress in 1919

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 18 January 2009