220 (number)
Natural number
From Wikipedia, the free encyclopedia
220 (two hundred [and] twenty) is the natural number following 219 and preceding 221
(two hundred twentieth)
| ||||
|---|---|---|---|---|
| Cardinal | two hundred twenty | |||
| Ordinal | 220th (two hundred twentieth) | |||
| Factorization | 22 × 5 × 11 | |||
| Divisors | 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220 | |||
| Greek numeral | ΣΚ´ | |||
| Roman numeral | CCXX, ccxx | |||
| Binary | 110111002 | |||
| Ternary | 220113 | |||
| Senary | 10046 | |||
| Octal | 3348 | |||
| Duodecimal | 16412 | |||
| Hexadecimal | DC16 | |||
In mathematics
It is a composite number, with its proper 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]
It is the sum of four consecutive primes (47 + 53 + 59 + 61).[4] 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.[5] There are exactly 220 different ways of partitioning 64 = 82 into a sum of square numbers.[6]
It is a tetrahedral number, the sum of the first ten triangular numbers,[7] and a dodecahedral number.[8] If all of the diagonals of a regular decagon are drawn, the resulting figure will have exactly 220 regions.[9]
It is the sum of the sums of the divisors of the first 16 positive integers.[10]