The number 10991
10991 is a composite number with 4 divisors. Its prime factorisation is 29 × 379. Divisors (4): 1, 29, 379, 10991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 10991: a semiprime: 29 × 379, the product of two primes.
- 2
10991 is composite. Its prime factorisation is
- 3
The divisors add up to 11400; without 10991 itself that is 409, so 10991 is deficient (409 is less than 10991). Euler's totient φ(10991) = 10584 numbers up to 10991 share no factor with it.
- 4
The digits of 10991 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 99 steps to reach 1.
LaTeX source of the formulas on this page
\[ 10991 = 29 \times 379 \]
10991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 11400 |
| Euler totient φ(n) | 10584 |
| Square | 120802081 |
| Cube | 1327735672271 |
| Square root | 104.837970 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 99 |
| Scientific notation | 1.0991 × |
10991 in other forms
| Form | Value |
|---|---|
| In words | ten thousand nine hundred and ninety-one |
| Binary (base 2) | 10101011101111 |
| Octal (base 8) | 25357 |
| Hexadecimal (base 16) | 2AEF |
| Base 3 | 120002002 |
| As time | 10991 seconds = 3 h 3 min 11 s |
Is 10991 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 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 | No (remainder 2) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 10991 a prime number?
No. 10991 = 29 × 379, so it is divisible by 29.
What are the factors of 10991?
1, 29, 379, 10991.
What is 10991 in binary?
10101011101111 (hexadecimal 2AEF, octal 25357).
What is the square root of 10991?
About 104.8380.
Is 10991 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 10991?
10991 is a semiprime: 29 × 379, the product of two primes.