The number 31878
31878 is a triangular number: 1 + 2 + … + 252 = 31878. Its prime factorisation is 2 × × 7 × 11 × 23. Divisors (48): 1, 2, 3, 6, 7, 9, 11, 14, 18, 21, 22, 23, 33, 42, 46, 63 … 31878.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31878: a triangular number: 1 + 2 + … + 252 = 31878.
- 2
31878 is composite. Its prime factorisation is
- 3
The divisors add up to 89856; without 31878 itself that is 57978, so 31878 is abundant (57978 is more than 31878). Euler's totient φ(31878) = 7920 numbers up to 31878 share no factor with it.
- 4
The digits of 31878 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 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31878 = 2 \times 3^{2} \times 7 \times 11 \times 23 \]31878 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 89856 |
| Euler totient φ(n) | 7920 |
| Square | 1016206884 |
| Cube | 32394643048152 |
| Square root | 178.544112 (= 3√3542) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1878 × |
31878 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and seventy-eight |
| Binary (base 2) | 111110010000110 |
| Octal (base 8) | 76206 |
| Hexadecimal (base 16) | 7C86 |
| Base 3 | 1121201200 |
| As time | 31878 seconds = 8 h 51 min 18 s |
Is 31878 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31878 ÷ 2 = 15939) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31878 ÷ 3 = 10626) | 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 | Yes (31878 ÷ 6 = 5313) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (31878 ÷ 7 = 4554) | 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 | Yes (31878 ÷ 9 = 3542) | 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 | Yes (31878 ÷ 11 = 2898) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31878 a prime number?
No. 31878 = 2 × × 7 × 11 × 23, so it is divisible by 2.
What are the factors of 31878?
1, 2, 3, 6, 7, 9, 11, 14, 18, 21, 22, 23, 33, 42, 46, 63, 66, 69, 77, 99, 126, 138, 154, 161, 198, 207, 231, 253, 322, 414, 462, 483, 506, 693, 759, 966, 1386, 1449, 1518, 1771, 2277, 2898, 3542, 4554, 5313, 10626, 15939, 31878.
What is 31878 in binary?
111110010000110 (hexadecimal 7C86, octal 76206).
What is the square root of 31878?
About 178.5441, exactly 3√3542.
Is 31878 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 31878?
31878 is a triangular number: 1 + 2 + … + 252 = 31878.