### About the Number 153 (one hundred fifty-three)

On 10 July 2009, Google morphed its logo to celebrate the birth of Nikola Telsa in 1856 (i.e. `153` years ago). Telsa was an electricity guru.

A couple of days earlier, MathBabbler was updating the nBAB for the number seven. While doing that he learned that seven was a narcissistic number. On 9 July 2009, MathBabbler posted a BAB announcing that the MBNA (MathBabbler Number Analyst) was modified to check for narcissistic numbers. MathBabbler used the number `153` to test the MBNA because `153` is a narcissistic number.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
153 is a natural, whole, integer
153 is odd
153 proper divisors are: 1,3,9,17,51,
153 is deficient (sum of divisors is 81)
153 is unhappy
153 is a Harshad number
153 is not prime
153 has the prime factors: 3*3*17 (sum=23)
153 sum of prime factors is: 23
153 and 154 are a Ruth-Aaron pair (distinct prime factors)
153 is narcissistic
153 in octal is 0231
153 in hexadecimal is 0x99
153 in binary is 10011001 (is evil)
153 nearest square numbers: -9...16 (144...169 )
sqrt(153) = 12.3693
ln(153) = 5.03044
log(153) = 2.18469
153 reciprocal is .00653594771241830065359477124183
153! is 2.00634e+269
153 is 48.7014 Pi years
153 is 7 score and 13 years
153 written as a Roman numeral is CLIII
```

`[WolframAlpha.com]` `153` has a representation as a sum of 2 squares: 3^2+12^2

`[NUmberGossip.com]` `153` is a vampire number.

On 10 June 2009, the MBNA did not check for vampire numbers.

OEIS.org::id:A020342, which states "Vampire numbers (definition 1): n has a nontrivial factorization using n's digits."

```     126,   153,   688,  1206,  1255,  1260,  1395,  1435,  1503,
1530,  1827,  2187,  3159,  3784,  6880, 10251, 10255, 10426,
10521, 10525, 10575, 11259, 11439, 11844, 11848, 12006, 12060,
12384, 12505, 12546, 12550, 12595, 12600, 12762, 12768, 12798,
12843, 12955, 12964...
```

Let's check and see why `153` is a vampire number.

```   the digits of 153 are 1, 5, 3 and 153 = 51 * 3

let's check 126...
the digits of 126 are 1, 2, 6 and 126 = 21 * 6

let's check 1827...
the digits of 1827 are 1, 8, 2, 7 and 1827 = 21 * 87
```

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 10 July 2009 