The number 21489
21489 is a composite number with 16 divisors. Its prime factorisation is 3 × 13 × 19 × 29. Divisors (16): 1, 3, 13, 19, 29, 39, 57, 87, 247, 377, 551, 741, 1131, 1653, 7163, 21489.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21489 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21489 is composite. Its prime factorisation is
- 3
The divisors add up to 33600; without 21489 itself that is 12111, so 21489 is deficient (12111 is less than 21489). Euler's totient φ(21489) = 12096 numbers up to 21489 share no factor with it.
- 4
The digits of 21489 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21489 = 3 \times 13 \times 19 \times 29 \]
21489 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 33600 |
| Euler totient φ(n) | 12096 |
| Square | 461777121 |
| Cube | 9923128553169 |
| Square root | 146.591268 |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.1489 × |
21489 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and eighty-nine |
| Binary (base 2) | 101001111110001 |
| Octal (base 8) | 51761 |
| Hexadecimal (base 16) | 53F1 |
| Base 3 | 1002110220 |
| As time | 21489 seconds = 5 h 58 min 9 s |
Is 21489 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 | Yes (21489 ÷ 3 = 7163) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 6) | 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 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21489 a prime number?
No. 21489 = 3 × 13 × 19 × 29, so it is divisible by 3.
What are the factors of 21489?
1, 3, 13, 19, 29, 39, 57, 87, 247, 377, 551, 741, 1131, 1653, 7163, 21489.
What is 21489 in binary?
101001111110001 (hexadecimal 53F1, octal 51761).
What is the square root of 21489?
About 146.5913.
Is 21489 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 21489?
It is a composite number with 16 divisors.