The number 21359
21359 is a composite number with 8 divisors. Its prime factorisation is 13 × 31 × 53. Divisors (8): 1, 13, 31, 53, 403, 689, 1643, 21359.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21359 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21359 is composite. Its prime factorisation is
- 3
The divisors add up to 24192; without 21359 itself that is 2833, so 21359 is deficient (2833 is less than 21359). Euler's totient φ(21359) = 18720 numbers up to 21359 share no factor with it.
- 4
The digits of 21359 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 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21359 = 13 \times 31 \times 53 \]
21359 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 24192 |
| Euler totient φ(n) | 18720 |
| Square | 456206881 |
| Cube | 9744122771279 |
| Square root | 146.147186 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1359 × |
21359 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and fifty-nine |
| Binary (base 2) | 101001101101111 |
| Octal (base 8) | 51557 |
| Hexadecimal (base 16) | 536F |
| Base 3 | 1002022002 |
| As time | 21359 seconds = 5 h 55 min 59 s |
Is 21359 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 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 7) | 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 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21359 a prime number?
No. 21359 = 13 × 31 × 53, so it is divisible by 13.
What are the factors of 21359?
1, 13, 31, 53, 403, 689, 1643, 21359.
What is 21359 in binary?
101001101101111 (hexadecimal 536F, octal 51557).
What is the square root of 21359?
About 146.1472.
Is 21359 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 21359?
It is a composite number with 8 divisors.