The number 31191
31191 is a composite number with 8 divisors. Its prime factorisation is 3 × 37 × 281. Divisors (8): 1, 3, 37, 111, 281, 843, 10397, 31191.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31191 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31191 is composite. Its prime factorisation is
- 3
The divisors add up to 42864; without 31191 itself that is 11673, so 31191 is deficient (11673 is less than 31191). Euler's totient φ(31191) = 20160 numbers up to 31191 share no factor with it.
- 4
The digits of 31191 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 222 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31191 = 3 \times 37 \times 281 \]
31191 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 42864 |
| Euler totient φ(n) | 20160 |
| Square | 972878481 |
| Cube | 30345052700871 |
| Square root | 176.609739 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 222 |
| Scientific notation | 3.1191 × |
31191 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand one hundred and ninety-one |
| Binary (base 2) | 111100111010111 |
| Octal (base 8) | 74727 |
| Hexadecimal (base 16) | 79D7 |
| Base 3 | 1120210020 |
| As time | 31191 seconds = 8 h 39 min 51 s |
Is 31191 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 (31191 ÷ 3 = 10397) | 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 | No (remainder 6) | 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 6) | 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 31191 a prime number?
No. 31191 = 3 × 37 × 281, so it is divisible by 3.
What are the factors of 31191?
1, 3, 37, 111, 281, 843, 10397, 31191.
What is 31191 in binary?
111100111010111 (hexadecimal 79D7, octal 74727).
What is the square root of 31191?
About 176.6097.
Is 31191 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 31191?
It is a composite number with 8 divisors.