The number 31187
31187 is a composite number with 4 divisors. Its prime factorisation is 13 × 2399. Divisors (4): 1, 13, 2399, 31187.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31187: a semiprime: 13 × 2399, the product of two primes.
- 2
31187 is composite. Its prime factorisation is
- 3
The divisors add up to 33600; without 31187 itself that is 2413, so 31187 is deficient (2413 is less than 31187). Euler's totient φ(31187) = 28776 numbers up to 31187 share no factor with it.
- 4
The digits of 31187 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 85 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31187 = 13 \times 2399 \]
31187 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 33600 |
| Euler totient φ(n) | 28776 |
| Square | 972628969 |
| Cube | 30333379656203 |
| Square root | 176.598414 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1187 × |
31187 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand one hundred and eighty-seven |
| Binary (base 2) | 111100111010011 |
| Octal (base 8) | 74723 |
| Hexadecimal (base 16) | 79D3 |
| Base 3 | 1120210002 |
| As time | 31187 seconds = 8 h 39 min 47 s |
Is 31187 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 2) | 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 7) | 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 31187 a prime number?
No. 31187 = 13 × 2399, so it is divisible by 13.
What are the factors of 31187?
1, 13, 2399, 31187.
What is 31187 in binary?
111100111010011 (hexadecimal 79D3, octal 74723).
What is the square root of 31187?
About 176.5984.
Is 31187 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 31187?
31187 is a semiprime: 13 × 2399, the product of two primes.