The number 12981
12981 is a composite number with 4 divisors. Its prime factorisation is 3 × 4327. Divisors (4): 1, 3, 4327, 12981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 12981: a semiprime: 3 × 4327, the product of two primes.
- 2
12981 is composite. Its prime factorisation is
- 3
The divisors add up to 17312; without 12981 itself that is 4331, so 12981 is deficient (4331 is less than 12981). Euler's totient φ(12981) = 8652 numbers up to 12981 share no factor with it.
- 4
The digits of 12981 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 138 steps to reach 1.
LaTeX source of the formulas on this page
\[ 12981 = 3 \times 4327 \]
12981 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 17312 |
| Euler totient φ(n) | 8652 |
| Square | 168506361 |
| Cube | 2187381072141 |
| Square root | 113.934192 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 138 |
| Scientific notation | 1.2981 × |
12981 in other forms
| Form | Value |
|---|---|
| In words | twelve thousand nine hundred and eighty-one |
| Binary (base 2) | 11001010110101 |
| Octal (base 8) | 31265 |
| Hexadecimal (base 16) | 32B5 |
| Base 3 | 122210210 |
| As time | 12981 seconds = 3 h 36 min 21 s |
Is 12981 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 | Yes (12981 ÷ 3 = 4327) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 3) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 12981 a prime number?
No. 12981 = 3 × 4327, so it is divisible by 3.
What are the factors of 12981?
1, 3, 4327, 12981.
What is 12981 in binary?
11001010110101 (hexadecimal 32B5, octal 31265).
What is the square root of 12981?
About 113.9342.
Is 12981 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 12981?
12981 is a semiprime: 3 × 4327, the product of two primes.