### About the Number 145 (one hundred forty-five)

This nBAB for `145` was created because MathBabbler was in the mood to create a nBAB and `145` was the smallest number without a nBAB.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
145 is a natural, whole, integer
145 is odd
145 proper divisors are: 1,5,29,
145 is deficient (sum of divisors is 35)
145 is unhappy
145 is not a Harshad number
145 is not prime
145 has the prime factors: 5*29 (sum=34)
145 is semiprime (biprime or 2-almost prime)
145 sum of prime factors is: 34
145 is ThurmNumber
145 is a Leyland number (3^4+4^3)
145 in octal is 0221
145 in hexadecimal is 0x91
145 in binary is 10010001 (is odious)
145 nearest square numbers: -1...24 (144...169 )
sqrt(145) = 12.0416
ln(145) = 4.97673
log(145) = 2.16137
145 reciprocal is .00689655172413793103448275862068
145! is 8.04793e+251
145 is 46.1549 Pi years
145 is 7 score and 5 years
145 written as a Roman numeral is CXLV
145 = 73^2 - 72^2 and 73 + 72 = 145
```

NumberGossip.com reported that "`145` is the smallest number (besides the trivial cases of 1 and 2) that is the sum of the factorials of its digits (1!+4!+5!).

NumDic.com reported that `145` is a pentagonal number and that it is the sum of two squares (9^2+8^2).

OEIS.org::id:A000326.

```   Pentagonal numbers: n(3n-1)/2

0, 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, 176, 210,
247, 287, 330, 376, 425, 477, 532, 590, 651, 715, 782,
852, 925, 1001, 1080, 1162, 1247, 1335, 1426, 1520,
1617, 1717, 1820, 1926, 2035, 2147, ...

n is a pentagonal number if...  (sqrt(24n+1) + 1)/6
evaluates to a whole number
```

The creation of this nBAB for the number `145` prompted MathBabbler to write this C++ program that checks if a number is a pentagonal number. This program has been added to the MBNA (MathBabbler Number Analyst).

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 11 March 2010 