The number 21536
21536 is a composite number with 12 divisors. Its prime factorisation is × 673. Divisors (12): 1, 2, 4, 8, 16, 32, 673, 1346, 2692, 5384, 10768, 21536.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21536 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21536 is composite. Its prime factorisation is
- 3
The divisors add up to 42462; without 21536 itself that is 20926, so 21536 is deficient (20926 is less than 21536). Euler's totient φ(21536) = 10752 numbers up to 21536 share no factor with it.
- 4
The digits of 21536 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21536 = 2^{5} \times 673 \]21536 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 42462 |
| Euler totient φ(n) | 10752 |
| Square | 463799296 |
| Cube | 9988381638656 |
| Square root | 146.751491 (= 4√1346) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.1536 × |
21536 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and thirty-six |
| Binary (base 2) | 101010000100000 |
| Octal (base 8) | 52040 |
| Hexadecimal (base 16) | 5420 |
| Base 3 | 1002112122 |
| As time | 21536 seconds = 5 h 58 min 56 s |
Is 21536 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21536 ÷ 2 = 10768) | 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 (21536 ÷ 4 = 5384) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | 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 4) | 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 (21536 ÷ 8 = 2692) | 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 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 21536 a prime number?
No. 21536 = × 673, so it is divisible by 2.
What are the factors of 21536?
1, 2, 4, 8, 16, 32, 673, 1346, 2692, 5384, 10768, 21536.
What is 21536 in binary?
101010000100000 (hexadecimal 5420, octal 52040).
What is the square root of 21536?
About 146.7515, exactly 4√1346.
Is 21536 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21536?
It is a composite number with 12 divisors.