### About the Number 191 (one hundred ninety-one)

While updating the Eisenstein Primes collection to include the number 593, MathBabbler noticed that there wasn't a nBAB for the number `191`. Note: `191` is also an Eisenstein prime.

RoadHacker has done lots of roadtripping on US Hwy-`191`.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
191 is a natural, whole, integer
191 is odd
191 proper divisors are: 1,
191 is deficient (sum of divisors is 1)
191 is unhappy
191 is not a Harshad number
191 is prime
...Sexy prime with 197
...Sophie Germain prime with 383
...Twin prime with 193
...OEIS:002145 (4n+3; n=47)
...Super
...Right-truncatable
...Eisenstein
...prime triplet {191, 193, 197}
...prime quadruplet {191, 193, 197, 199}
191 is undulating
191 is palindromic
191 is a Thabit number
191 in octal is 0277
191 in binary is 10111111 (is odious)
191 nearest square numbers: -22...5 (169...196 [14])
sqrt(191) = 13.8203
ln(191) = 5.25227
log(191) = 2.28103
191 reciprocal is .00523560209424083769633507853403
191! is 1.84894e+354
191 is 60.7972 Pi years
191 is 9 score and 11 years
191 written as a Roman numeral is CXCI
```

`191` is a Sexy prime with 197 and 197 is an Eisenstein prime.

`191` is a Sophie Germain prime with 383 and 383 is an Eisenstein prime.

The following items were copied from NumberGossip.com.

```   191 is the smallest palindromic prime whose sum of digits
is a multidigit palindromic prime

By adding up the values of the common US coins, one obtains
191 cents. (silver dollar + half dollar + quarter +
dime + nickel + penny)
```

`191`16 equals 401 and 401 is an Eisenstein prime.

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 11 July 2009