The number 17981
17981 is the 2062nd prime number. Its only divisors are 1 and 17981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 17981: the 2062nd prime number.
- 2
17981 is prime, so its only factors are 1 and 17981. It is the 2062nd prime; the next prime is 17987 and the one before is 17977.
- 3
The divisors add up to 17982; without 17981 itself that is 1, so 17981 is deficient (1 is less than 17981). Euler's totient φ(17981) = 17980 numbers up to 17981 share no factor with it.
- 4
The digits of 17981 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 79 steps to reach 1.
17981 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 17982 |
| Euler totient φ(n) | 17980 |
| Square | 323316361 |
| Cube | 5813551487141 |
| Square root | 134.093251 |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 79 |
| Scientific notation | 1.7981 × |
17981 in other forms
| Form | Value |
|---|---|
| In words | seventeen thousand nine hundred and eighty-one |
| Binary (base 2) | 100011000111101 |
| Octal (base 8) | 43075 |
| Hexadecimal (base 16) | 463D |
| Base 3 | 220122222 |
| As time | 17981 seconds = 4 h 59 min 41 s |
Is 17981 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 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 5) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 17981 a prime number?
Yes. 17981 is divisible only by 1 and itself.
What are the factors of 17981?
1, 17981.
What is 17981 in binary?
100011000111101 (hexadecimal 463D, octal 43075).
What is the square root of 17981?
About 134.0933.
Is 17981 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 17981?
17981 is the 2062nd prime number.