The number 31887
31887 is a composite number with 8 divisors. Its prime factorisation is × 1181. Divisors (8): 1, 3, 9, 27, 1181, 3543, 10629, 31887.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31887: a Harshad number: divisible by its digit sum 27.
- 2
31887 is composite. Its prime factorisation is
- 3
The divisors add up to 47280; without 31887 itself that is 15393, so 31887 is deficient (15393 is less than 31887). Euler's totient φ(31887) = 21240 numbers up to 31887 share no factor with it.
- 4
The digits of 31887 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31887 = 3^{3} \times 1181 \]31887 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 47280 |
| Euler totient φ(n) | 21240 |
| Square | 1016780769 |
| Cube | 32422088381103 |
| Square root | 178.569314 (= 3√3543) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.1887 × |
31887 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and eighty-seven |
| Binary (base 2) | 111110010001111 |
| Octal (base 8) | 76217 |
| Hexadecimal (base 16) | 7C8F |
| Base 3 | 1121202000 |
| As time | 31887 seconds = 8 h 51 min 27 s |
Is 31887 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 (31887 ÷ 3 = 10629) | 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 3) | 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 | Yes (31887 ÷ 9 = 3543) | 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 9) | 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 31887 a prime number?
No. 31887 = × 1181, so it is divisible by 3.
What are the factors of 31887?
1, 3, 9, 27, 1181, 3543, 10629, 31887.
What is 31887 in binary?
111110010001111 (hexadecimal 7C8F, octal 76217).
What is the square root of 31887?
About 178.5693, exactly 3√3543.
Is 31887 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 31887?
31887 is a Harshad number: divisible by its digit sum 27.