To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

# 220 (number)

 ← 219 220 221 →
Cardinaltwo hundred twenty
Ordinal220th
(two hundred twentieth)
Factorization22× 5 × 11
Greek numeralΣΚ´
Roman numeralCCXX
Binary110111002
Ternary220113
Quaternary31304
Quinary13405
Senary10046
Octal3348
Duodecimal16412
VigesimalB020
Base 366436

220 (two hundred [and] twenty) is the natural number following 219 and preceding 221.

## In mathematics

It is a composite number, with its divisors being 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110, making it an amicable number with 284.[1][2] Every number up to 220 may be expressed as a sum of its divisors, making 220 a practical number.[3] Also, being divisible by the sum of its digits, 220 is a Harshad number.[4]

It is the sum of four consecutive primes (47 + 53 + 59 + 61).[5] It is the smallest even number with the property that when represented as a sum of two prime numbers (per Goldbach's conjecture) both of the primes must be greater than or equal to 23.[6] There are exactly 220 different ways of partitioning 64 = 82 into a sum of square numbers.[7]

It is a tetrahedral number, the sum of the first ten triangular numbers,[8] and a dodecahedral number.[9] If all of the diagonals of a regular decagon are drawn, the resulting figure will have exactly 220 regions.[10]

It is the sum of the sums of the divisors of the first 16 positive integers.[11]

## In other fields

The number 220 can also refer to:

## Notes

1. ^ Bryan Bunch, The Kingdom of Infinite Number. New York: W. H. Freeman & Company (2000): 167
2. ^ Higgins, Peter (2008). Number Story: From Counting to Cryptography. New York: Copernicus. p. 61. ISBN 978-1-84800-000-1.
3. ^ Sloane, N. J. A. (ed.). "Sequence A005153 (Practical numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. ^
5. ^ Sloane, N. J. A. (ed.). "Sequence A034963 (Sums of four consecutive primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. ^
7. ^ Sloane, N. J. A. (ed.). "Sequence A037444 (Number of partitions of n^2 into squares)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
8. ^ Sloane, N. J. A. (ed.). "Sequence A000292 (Tetrahedral (or triangular pyramidal) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
9. ^ Sloane, N. J. A. (ed.). "Sequence A006566 (Dodecahedral numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
10. ^
11. ^