The number 31831
31831 is a composite number with 4 divisors. Its prime factorisation is 139 × 229. Divisors (4): 1, 139, 229, 31831.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31831: a semiprime: 139 × 229, the product of two primes.
- 2
31831 is composite. Its prime factorisation is
- 3
The divisors add up to 32200; without 31831 itself that is 369, so 31831 is deficient (369 is less than 31831). Euler's totient φ(31831) = 31464 numbers up to 31831 share no factor with it.
- 4
The digits of 31831 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 98 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31831 = 139 \times 229 \]
31831 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 32200 |
| Euler totient φ(n) | 31464 |
| Square | 1013212561 |
| Cube | 32251569029191 |
| Square root | 178.412444 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 98 |
| Scientific notation | 3.1831 × |
31831 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and thirty-one |
| Binary (base 2) | 111110001010111 |
| Octal (base 8) | 76127 |
| Hexadecimal (base 16) | 7C57 |
| Base 3 | 1121122221 |
| As time | 31831 seconds = 8 h 50 min 31 s |
Is 31831 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 1) | 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 1) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31831 a prime number?
No. 31831 = 139 × 229, so it is divisible by 139.
What are the factors of 31831?
1, 139, 229, 31831.
What is 31831 in binary?
111110001010111 (hexadecimal 7C57, octal 76127).
What is the square root of 31831?
About 178.4124.
Is 31831 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 31831?
31831 is a semiprime: 139 × 229, the product of two primes.