The number 26991
26991 is a composite number with 6 divisors. Its prime factorisation is × 2999. Divisors (6): 1, 3, 9, 2999, 8997, 26991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 26991: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
26991 is composite. Its prime factorisation is
- 3
The divisors add up to 39000; without 26991 itself that is 12009, so 26991 is deficient (12009 is less than 26991). Euler's totient φ(26991) = 17988 numbers up to 26991 share no factor with it.
- 4
The digits of 26991 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 77 steps to reach 1.
LaTeX source of the formulas on this page
\[ 26991 = 3^{2} \times 2999 \]26991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 39000 |
| Euler totient φ(n) | 17988 |
| Square | 728514081 |
| Cube | 19663323560271 |
| Square root | 164.289379 (= 3√2999) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 77 |
| Scientific notation | 2.6991 × |
26991 in other forms
| Form | Value |
|---|---|
| In words | twenty-six thousand nine hundred and ninety-one |
| Binary (base 2) | 110100101101111 |
| Octal (base 8) | 64557 |
| Hexadecimal (base 16) | 696F |
| Base 3 | 1101000200 |
| As time | 26991 seconds = 7 h 29 min 51 s |
Is 26991 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 (26991 ÷ 3 = 8997) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (26991 ÷ 9 = 2999) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 26991 a prime number?
No. 26991 = × 2999, so it is divisible by 3.
What are the factors of 26991?
1, 3, 9, 2999, 8997, 26991.
What is 26991 in binary?
110100101101111 (hexadecimal 696F, octal 64557).
What is the square root of 26991?
About 164.2894, exactly 3√2999.
Is 26991 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 26991?
26991 is a happy number: repeatedly adding the squares of its digits reaches 1.