The number 31691
31691 is a composite number with 8 divisors. Its prime factorisation is 11 × 43 × 67. Divisors (8): 1, 11, 43, 67, 473, 737, 2881, 31691.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31691 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31691 is composite. Its prime factorisation is
- 3
The divisors add up to 35904; without 31691 itself that is 4213, so 31691 is deficient (4213 is less than 31691). Euler's totient φ(31691) = 27720 numbers up to 31691 share no factor with it.
- 4
The digits of 31691 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 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31691 = 11 \times 43 \times 67 \]
31691 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 35904 |
| Euler totient φ(n) | 27720 |
| Square | 1004319481 |
| Cube | 31827888672371 |
| Square root | 178.019662 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1691 × |
31691 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand six hundred and ninety-one |
| Binary (base 2) | 111101111001011 |
| Octal (base 8) | 75713 |
| Hexadecimal (base 16) | 7BCB |
| Base 3 | 1121110202 |
| As time | 31691 seconds = 8 h 48 min 11 s |
Is 31691 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 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 3) | 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 | Yes (31691 ÷ 11 = 2881) | 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 31691 a prime number?
No. 31691 = 11 × 43 × 67, so it is divisible by 11.
What are the factors of 31691?
1, 11, 43, 67, 473, 737, 2881, 31691.
What is 31691 in binary?
111101111001011 (hexadecimal 7BCB, octal 75713).
What is the square root of 31691?
About 178.0197.
Is 31691 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 31691?
It is a composite number with 8 divisors.