The number 23981
23981 is the 2667th prime number. Its only divisors are 1 and 23981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 23981: the 2667th prime number.
- 2
23981 is prime, so its only factors are 1 and 23981. It is the 2667th prime; the next prime is 23993 and the one before is 23977.
- 3
The divisors add up to 23982; without 23981 itself that is 1, so 23981 is deficient (1 is less than 23981). Euler's totient φ(23981) = 23980 numbers up to 23981 share no factor with it.
- 4
The digits of 23981 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 82 steps to reach 1.
23981 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 23982 |
| Euler totient φ(n) | 23980 |
| Square | 575088361 |
| Cube | 13791193985141 |
| Square root | 154.857999 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 82 |
| Scientific notation | 2.3981 × |
23981 in other forms
| Form | Value |
|---|---|
| In words | twenty-three thousand nine hundred and eighty-one |
| Binary (base 2) | 101110110101101 |
| Octal (base 8) | 56655 |
| Hexadecimal (base 16) | 5DAD |
| Base 3 | 1012220012 |
| As time | 23981 seconds = 6 h 39 min 41 s |
Is 23981 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 1) | 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 6) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 23981 a prime number?
Yes. 23981 is divisible only by 1 and itself.
What are the factors of 23981?
1, 23981.
What is 23981 in binary?
101110110101101 (hexadecimal 5DAD, octal 56655).
What is the square root of 23981?
About 154.8580.
Is 23981 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 23981?
23981 is the 2667th prime number.