The number 21584
21584 is a composite number with 20 divisors. Its prime factorisation is × 19 × 71. Divisors (20): 1, 2, 4, 8, 16, 19, 38, 71, 76, 142, 152, 284, 304, 568, 1136, 1349 … 21584.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21584 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21584 is composite. Its prime factorisation is
- 3
The divisors add up to 44640; without 21584 itself that is 23056, so 21584 is abundant (23056 is more than 21584). Euler's totient φ(21584) = 10080 numbers up to 21584 share no factor with it.
- 4
The digits of 21584 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 118 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21584 = 2^{4} \times 19 \times 71 \]21584 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 44640 |
| Euler totient φ(n) | 10080 |
| Square | 465869056 |
| Cube | 10055317704704 |
| Square root | 146.914941 (= 4√1349) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 118 |
| Scientific notation | 2.1584 × |
21584 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and eighty-four |
| Binary (base 2) | 101010001010000 |
| Octal (base 8) | 52120 |
| Hexadecimal (base 16) | 5450 |
| Base 3 | 1002121102 |
| As time | 21584 seconds = 5 h 59 min 44 s |
Is 21584 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21584 ÷ 2 = 10792) | 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 | Yes (21584 ÷ 4 = 5396) | 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 2) | 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 | Yes (21584 ÷ 8 = 2698) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 4) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21584 a prime number?
No. 21584 = × 19 × 71, so it is divisible by 2.
What are the factors of 21584?
1, 2, 4, 8, 16, 19, 38, 71, 76, 142, 152, 284, 304, 568, 1136, 1349, 2698, 5396, 10792, 21584.
What is 21584 in binary?
101010001010000 (hexadecimal 5450, octal 52120).
What is the square root of 21584?
About 146.9149, exactly 4√1349.
Is 21584 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 21584?
It is a composite number with 20 divisors.