### About the Number 81 (eighty-one)

##### Why Babble About 81?

On 24 February 2006, Dennis Weaver died at the age of `81`.

On 24 February 2006, Don Knotts died at the age of `81`.

[side-bar] On 25 February 2006, Darren McGavin died at the age of `83`.

For many years, I have predicted my death date to be 18 January 2038. If this holds true, then I will die at the age of `81`. { countdowns to special GDT dates} {tombstone}

```   81 is positive
81 is odd
81 is the opposite of -81
81 prime factorization is 3 3 3 3 (34)
81 is a perfect square (9x9) (92)
[perfect square is a number whose square root is an integer]

the sum of the digits of 81 equals the sqrt(81)
[8+1 = sqrt(81) = 9]

81st day of a non-leap year is on March 22nd
```

Wikipedia.org:: 81 (number)

`81 + 1` equals 82

```   Interstate 81 passes through Tennessee, Virginia,
West Virginia, Maryland, Pennsylvania, New York
US Hwy-81 passes through North Dakota, South Dakota,
Nebraska, Kansas, Oklahoma, and Texas
AZ Hwy-81 existed from 1927-1938 [source: ArizonaRoads.com]
```
##### Update::2008.12.26

Eartha Kitt died on 25 December 2008 at the age of `81`. MathBabbler used Kitt's death to update this nBAB with output obtained from the MBNA (MathBabbler Number Analyst).

```   MathBabbler Number Analyst (MBNA) output:
=========================================
81 is a natural, whole, integer
81 is odd
81 proper divisors are: 1,3,9,27,
81 is deficient (sum of divisors is 40)
81 is unhappy
81 is a Harshad number
81 is not prime
81 is undulating
81 has the prime factors: 3*3*3*3
81 in octal is 0121
81 in hexadecimal is 0x51
81 in binary is 1010001 (is odious)
81 nearest square numbers: 81 is square (81 is square)
sqrt(81) = 9
ln(81) = 4.39445
log(81) = 1.90849
81 is 3^4
81 is 9^2
81 reciprocal is .01234567901234567901234567901234
81! is 5.79713e+120
81 is 25.7831 Pi years
81 is 4 score and 1 year
81 written as a Roman numeral is LXXXI
```

MathBabbler was 51 years young with Eartha died. 51 in base-16 is `81` in base-10.

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 27 February 2006 