The number 21537
21537 is a composite number with 6 divisors. Its prime factorisation is × 2393. Divisors (6): 1, 3, 9, 2393, 7179, 21537.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21537 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21537 is composite. Its prime factorisation is
- 3
The divisors add up to 31122; without 21537 itself that is 9585, so 21537 is deficient (9585 is less than 21537). Euler's totient φ(21537) = 14352 numbers up to 21537 share no factor with it.
- 4
The digits of 21537 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 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21537 = 3^{2} \times 2393 \]21537 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 31122 |
| Euler totient φ(n) | 14352 |
| Square | 463842369 |
| Cube | 9989773101153 |
| Square root | 146.754898 (= 3√2393) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1537 × |
21537 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and thirty-seven |
| Binary (base 2) | 101010000100001 |
| Octal (base 8) | 52041 |
| Hexadecimal (base 16) | 5421 |
| Base 3 | 1002112200 |
| As time | 21537 seconds = 5 h 58 min 57 s |
Is 21537 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 (21537 ÷ 3 = 7179) | 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 2) | 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 5) | 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 | Yes (21537 ÷ 9 = 2393) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21537 a prime number?
No. 21537 = × 2393, so it is divisible by 3.
What are the factors of 21537?
1, 3, 9, 2393, 7179, 21537.
What is 21537 in binary?
101010000100001 (hexadecimal 5421, octal 52041).
What is the square root of 21537?
About 146.7549, exactly 3√2393.
Is 21537 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 21537?
It is a composite number with 6 divisors.