# 230 (number)

230 (two hundred [and] thirty) is the natural number following 229 and preceding 231.

 ← 229 230 231 →
Cardinaltwo hundred thirty
Ordinal230th
(two hundred thirtieth)
Factorization2 × 5 × 23
Greek numeralΣΛ´
Roman numeralCCXXX
Binary111001102
Ternary221123
Senary10226
Octal3468
Duodecimal17212

• a composite number, with its divisors being 2, 5, 10, 23, 46, and 115.
• a sphenic number[1] because it is the product of 3 primes. It is also the first sphenic number to immediately precede another sphenic number.
• palindromic and a repdigit in bases 22 (AA22), 45 (5545), 114 (22114), 229 (11229)
• a Harshad number in bases 2, 6, 10, 12, 23 (and 16 other bases).
• a happy number.[2]
• a nontotient[3] since there is no integer with 230 coprimes below it.
• the sum of the coprime counts for the first 27 integers.
• the aliquot sum of both 454 and 52441.
• part of the 41-aliquot tree.
• the maximal number of pieces that can be obtained by cutting an annulus with 20 cuts.[4]

The aliquot sequence starting at 224 is: 224, 280, 440, 640, 890, 730, 602, 454, 230, 202, 104, 106, 56, 64, 63, 41, 1, 0.

There are 230 unique space groups describing all possible crystal symmetries.

## References

1. ^ "Sloane's A007304 : Sphenic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-09-05.
2. ^ "Sloane's A007770 : Happy numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-09-05.
3. ^ "Sloane's A005277 : Nontotients". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-09-05.
4. ^ Sloane, N. J. A. (ed.). "Sequence A000096 (a(n) = n*(n+3)/2)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.