The number 27981
27981 is a composite number with 6 divisors. Its prime factorisation is × 3109. Divisors (6): 1, 3, 9, 3109, 9327, 27981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
27981 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
27981 is composite. Its prime factorisation is
- 3
The divisors add up to 40430; without 27981 itself that is 12449, so 27981 is deficient (12449 is less than 27981). Euler's totient φ(27981) = 18648 numbers up to 27981 share no factor with it.
- 4
The digits of 27981 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 108 steps to reach 1.
LaTeX source of the formulas on this page
\[ 27981 = 3^{2} \times 3109 \]27981 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 40430 |
| Euler totient φ(n) | 18648 |
| Square | 782936361 |
| Cube | 21907342317141 |
| Square root | 167.275222 (= 3√3109) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 108 |
| Scientific notation | 2.7981 × |
27981 in other forms
| Form | Value |
|---|---|
| In words | twenty-seven thousand nine hundred and eighty-one |
| Binary (base 2) | 110110101001101 |
| Octal (base 8) | 66515 |
| Hexadecimal (base 16) | 6D4D |
| Base 3 | 1102101100 |
| As time | 27981 seconds = 7 h 46 min 21 s |
Is 27981 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 (27981 ÷ 3 = 9327) | 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 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 | Yes (27981 ÷ 9 = 3109) | 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 8) | 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 27981 a prime number?
No. 27981 = × 3109, so it is divisible by 3.
What are the factors of 27981?
1, 3, 9, 3109, 9327, 27981.
What is 27981 in binary?
110110101001101 (hexadecimal 6D4D, octal 66515).
What is the square root of 27981?
About 167.2752, exactly 3√3109.
Is 27981 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 27981?
It is a composite number with 6 divisors.