The number 31918
31918 is a composite number with 4 divisors. Its prime factorisation is 2 × 15959. Divisors (4): 1, 2, 15959, 31918.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31918: a semiprime: 2 × 15959, the product of two primes.
- 2
31918 is composite. Its prime factorisation is
- 3
The divisors add up to 47880; without 31918 itself that is 15962, so 31918 is deficient (15962 is less than 31918). Euler's totient φ(31918) = 15958 numbers up to 31918 share no factor with it.
- 4
The digits of 31918 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31918 = 2 \times 15959 \]
31918 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 47880 |
| Euler totient φ(n) | 15958 |
| Square | 1018758724 |
| Cube | 32516740952632 |
| Square root | 178.656094 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1918 × |
31918 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand nine hundred and eighteen |
| Binary (base 2) | 111110010101110 |
| Octal (base 8) | 76256 |
| Hexadecimal (base 16) | 7CAE |
| Base 3 | 1121210011 |
| As time | 31918 seconds = 8 h 51 min 58 s |
Is 31918 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31918 ÷ 2 = 15959) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31918 a prime number?
No. 31918 = 2 × 15959, so it is divisible by 2.
What are the factors of 31918?
1, 2, 15959, 31918.
What is 31918 in binary?
111110010101110 (hexadecimal 7CAE, octal 76256).
What is the square root of 31918?
About 178.6561.
Is 31918 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 31918?
31918 is a semiprime: 2 × 15959, the product of two primes.