The number 21889
21889 is a composite number with 8 divisors. Its prime factorisation is 7 × 53 × 59. Divisors (8): 1, 7, 53, 59, 371, 413, 3127, 21889.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21889 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21889 is composite. Its prime factorisation is
- 3
The divisors add up to 25920; without 21889 itself that is 4031, so 21889 is deficient (4031 is less than 21889). Euler's totient φ(21889) = 18096 numbers up to 21889 share no factor with it.
- 4
The digits of 21889 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 118 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21889 = 7 \times 53 \times 59 \]
21889 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 25920 |
| Euler totient φ(n) | 18096 |
| Square | 479128321 |
| Cube | 10487639818369 |
| Square root | 147.949316 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 118 |
| Scientific notation | 2.1889 × |
21889 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and eighty-nine |
| Binary (base 2) | 101010110000001 |
| Octal (base 8) | 52601 |
| Hexadecimal (base 16) | 5581 |
| Base 3 | 1010000201 |
| As time | 21889 seconds = 6 h 4 min 49 s |
Is 21889 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21889 ÷ 7 = 3127) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21889 a prime number?
No. 21889 = 7 × 53 × 59, so it is divisible by 7.
What are the factors of 21889?
1, 7, 53, 59, 371, 413, 3127, 21889.
What is 21889 in binary?
101010110000001 (hexadecimal 5581, octal 52601).
What is the square root of 21889?
About 147.9493.
Is 21889 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 21889?
It is a composite number with 8 divisors.