The number 31280
31280 is a composite number with 40 divisors. Its prime factorisation is × 5 × 17 × 23. Divisors (40): 1, 2, 4, 5, 8, 10, 16, 17, 20, 23, 34, 40, 46, 68, 80, 85 … 31280.
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How to work it out
- 1
31280 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31280 is composite. Its prime factorisation is
- 3
The divisors add up to 80352; without 31280 itself that is 49072, so 31280 is abundant (49072 is more than 31280). Euler's totient φ(31280) = 11264 numbers up to 31280 share no factor with it.
- 4
The digits of 31280 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31280 = 2^{4} \times 5 \times 17 \times 23 \]31280 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 40 |
| Sum of divisors | 80352 |
| Euler totient φ(n) | 11264 |
| Square | 978438400 |
| Cube | 30605553152000 |
| Square root | 176.861528 (= 4√1955) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 103 |
| Scientific notation | 3.128 × |
31280 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and eighty |
| Binary (base 2) | 111101000110000 |
| Octal (base 8) | 75060 |
| Hexadecimal (base 16) | 7A30 |
| Base 3 | 1120220112 |
| As time | 31280 seconds = 8 h 41 min 20 s |
Is 31280 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31280 ÷ 2 = 15640) | 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 (31280 ÷ 4 = 7820) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31280 ÷ 5 = 6256) | 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 4) | 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 (31280 ÷ 8 = 3910) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (31280 ÷ 10 = 3128) | 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 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31280 a prime number?
No. 31280 = × 5 × 17 × 23, so it is divisible by 2.
What are the factors of 31280?
1, 2, 4, 5, 8, 10, 16, 17, 20, 23, 34, 40, 46, 68, 80, 85, 92, 115, 136, 170, 184, 230, 272, 340, 368, 391, 460, 680, 782, 920, 1360, 1564, 1840, 1955, 3128, 3910, 6256, 7820, 15640, 31280.
What is 31280 in binary?
111101000110000 (hexadecimal 7A30, octal 75060).
What is the square root of 31280?
About 176.8615, exactly 4√1955.
Is 31280 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 31280?
It is a composite number with 40 divisors.