The number 31880
31880 is a composite number with 16 divisors. Its prime factorisation is × 5 × 797. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 797, 1594, 3188, 3985, 6376, 7970, 15940, 31880.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31880: a Harshad number: divisible by its digit sum 20.
- 2
31880 is composite. Its prime factorisation is
- 3
The divisors add up to 71820; without 31880 itself that is 39940, so 31880 is abundant (39940 is more than 31880). Euler's totient φ(31880) = 12736 numbers up to 31880 share no factor with it.
- 4
The digits of 31880 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 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31880 = 2^{3} \times 5 \times 797 \]31880 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 71820 |
| Euler totient φ(n) | 12736 |
| Square | 1016334400 |
| Cube | 32400740672000 |
| Square root | 178.549713 (= 2√7970) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.188 × |
31880 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and eighty |
| Binary (base 2) | 111110010001000 |
| Octal (base 8) | 76210 |
| Hexadecimal (base 16) | 7C88 |
| Base 3 | 1121201202 |
| As time | 31880 seconds = 8 h 51 min 20 s |
Is 31880 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31880 ÷ 2 = 15940) | 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 | Yes (31880 ÷ 4 = 7970) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31880 ÷ 5 = 6376) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | 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 | Yes (31880 ÷ 8 = 3985) | 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 | Yes (31880 ÷ 10 = 3188) | 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 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31880 a prime number?
No. 31880 = × 5 × 797, so it is divisible by 2.
What are the factors of 31880?
1, 2, 4, 5, 8, 10, 20, 40, 797, 1594, 3188, 3985, 6376, 7970, 15940, 31880.
What is 31880 in binary?
111110010001000 (hexadecimal 7C88, octal 76210).
What is the square root of 31880?
About 178.5497, exactly 2√7970.
Is 31880 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 31880?
31880 is a Harshad number: divisible by its digit sum 20.