The number 21317
21317 is a twin prime (21317 and 21319 are both prime) and the 2393rd prime number. Its only divisors are 1 and 21317.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21317: a twin prime (21317 and 21319 are both prime); the 2393rd prime number.
- 2
21317 is prime, so its only factors are 1 and 21317. It is the 2393rd prime; the next prime is 21319 and the one before is 21313.
- 3
The divisors add up to 21318; without 21317 itself that is 1, so 21317 is deficient (1 is less than 21317). Euler's totient φ(21317) = 21316 numbers up to 21317 share no factor with it.
- 4
The digits of 21317 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
21317 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21318 |
| Euler totient φ(n) | 21316 |
| Square | 454414489 |
| Cube | 9686753662013 |
| Square root | 146.003425 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1317 × |
21317 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and seventeen |
| Binary (base 2) | 101001101000101 |
| Octal (base 8) | 51505 |
| Hexadecimal (base 16) | 5345 |
| Base 3 | 1002020112 |
| As time | 21317 seconds = 5 h 55 min 17 s |
Is 21317 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 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21317 a prime number?
Yes. 21317 is divisible only by 1 and itself.
What are the factors of 21317?
1, 21317.
What is 21317 in binary?
101001101000101 (hexadecimal 5345, octal 51505).
What is the square root of 21317?
About 146.0034.
Is 21317 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 21317?
21317 is a twin prime (21317 and 21319 are both prime); the 2393rd prime number.