The number 21689
21689 is a composite number with 6 divisors. Its prime factorisation is Ć 41. Divisors (6): 1, 23, 41, 529, 943, 21689.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21689 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21689 is composite. Its prime factorisation is
- 3
The divisors add up to 23226; without 21689 itself that is 1537, so 21689 is deficient (1537 is less than 21689). Euler's totient Ļ(21689) = 20240 numbers up to 21689 share no factor with it.
- 4
The digits of 21689 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 131 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21689 = 23^{2} \times 41 \]21689 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 23226 |
| Euler totient Ļ(n) | 20240 |
| Square | 470412721 |
| Cube | 10202781505769 |
| Square root | 147.271857 (= 23ā41) |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 131 |
| Scientific notation | 2.1689 Ć |
21689 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and eighty-nine |
| Binary (base 2) | 101010010111001 |
| Octal (base 8) | 52271 |
| Hexadecimal (base 16) | 54B9 |
| Base 3 | 1002202022 |
| As time | 21689 seconds = 6 h 1 min 29 s |
Is 21689 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 8) | 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 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21689 a prime number?
No. 21689 = Ć 41, so it is divisible by 23.
What are the factors of 21689?
1, 23, 41, 529, 943, 21689.
What is 21689 in binary?
101010010111001 (hexadecimal 54B9, octal 52271).
What is the square root of 21689?
About 147.2719, exactly 23ā41.
Is 21689 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 21689?
It is a composite number with 6 divisors.