221 (number)
Natural number
From Wikipedia, the free encyclopedia
221 (two hundred [and] twenty-one) is the natural number following 220 and preceding 222.
Cardinaltwo hundred twenty-one
Ordinal221st
(two hundred twenty-first)
(two hundred twenty-first)
Factorization13 × 17
Divisors1, 13, 17, 221
| ||||
|---|---|---|---|---|
| Cardinal | two hundred twenty-one | |||
| Ordinal | 221st (two hundred twenty-first) | |||
| Factorization | 13 × 17 | |||
| Divisors | 1, 13, 17, 221 | |||
| Greek numeral | ΣΚΑ´ | |||
| Roman numeral | CCXXI, ccxxi | |||
| Binary | 110111012 | |||
| Ternary | 220123 | |||
| Senary | 10056 | |||
| Octal | 3358 | |||
| Duodecimal | 16512 | |||
| Hexadecimal | DD16 | |||
In mathematics
Its factorization as 13 × 17 makes 221 the product of two consecutive prime numbers, the sixth smallest such product.[1]
221 is a centered square number,[2] an Ulam number,[3] and a brilliant number,[4] meaning that its prime factors have the same amount of digits.
