The number 21582
21582 is a composite number with 24 divisors. Its prime factorisation is 2 × × 11 × 109. Divisors (24): 1, 2, 3, 6, 9, 11, 18, 22, 33, 66, 99, 109, 198, 218, 327, 654 … 21582.
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How to work it out
- 1
What is special about 21582: a Harshad number: divisible by its digit sum 18.
- 2
21582 is composite. Its prime factorisation is
- 3
The divisors add up to 51480; without 21582 itself that is 29898, so 21582 is abundant (29898 is more than 21582). Euler's totient φ(21582) = 6480 numbers up to 21582 share no factor with it.
- 4
The digits of 21582 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21582 = 2 \times 3^{2} \times 11 \times 109 \]21582 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 51480 |
| Euler totient φ(n) | 6480 |
| Square | 465782724 |
| Cube | 10052522749368 |
| Square root | 146.908135 (= 3√2398) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.1582 × |
21582 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and eighty-two |
| Binary (base 2) | 101010001001110 |
| Octal (base 8) | 52116 |
| Hexadecimal (base 16) | 544E |
| Base 3 | 1002121100 |
| As time | 21582 seconds = 5 h 59 min 42 s |
Is 21582 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21582 ÷ 2 = 10791) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21582 ÷ 3 = 7194) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21582 ÷ 6 = 3597) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21582 ÷ 9 = 2398) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (21582 ÷ 11 = 1962) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21582 a prime number?
No. 21582 = 2 × × 11 × 109, so it is divisible by 2.
What are the factors of 21582?
1, 2, 3, 6, 9, 11, 18, 22, 33, 66, 99, 109, 198, 218, 327, 654, 981, 1199, 1962, 2398, 3597, 7194, 10791, 21582.
What is 21582 in binary?
101010001001110 (hexadecimal 544E, octal 52116).
What is the square root of 21582?
About 146.9081, exactly 3√2398.
Is 21582 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 21582?
21582 is a Harshad number: divisible by its digit sum 18.