The number 31480
31480 is a composite number with 16 divisors. Its prime factorisation is × 5 × 787. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 787, 1574, 3148, 3935, 6296, 7870, 15740, 31480.
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How to work it out
- 1
31480 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31480 is composite. Its prime factorisation is
- 3
The divisors add up to 70920; without 31480 itself that is 39440, so 31480 is abundant (39440 is more than 31480). Euler's totient φ(31480) = 12576 numbers up to 31480 share no factor with it.
- 4
The digits of 31480 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31480 = 2^{3} \times 5 \times 787 \]31480 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 70920 |
| Euler totient φ(n) | 12576 |
| Square | 990990400 |
| Cube | 31196377792000 |
| Square root | 177.426041 (= 2√7870) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 103 |
| Scientific notation | 3.148 × |
31480 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand four hundred and eighty |
| Binary (base 2) | 111101011111000 |
| Octal (base 8) | 75370 |
| Hexadecimal (base 16) | 7AF8 |
| Base 3 | 1121011221 |
| As time | 31480 seconds = 8 h 44 min 40 s |
Is 31480 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31480 ÷ 2 = 15740) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (31480 ÷ 4 = 7870) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31480 ÷ 5 = 6296) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 (31480 ÷ 8 = 3935) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (31480 ÷ 10 = 3148) | 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 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31480 a prime number?
No. 31480 = × 5 × 787, so it is divisible by 2.
What are the factors of 31480?
1, 2, 4, 5, 8, 10, 20, 40, 787, 1574, 3148, 3935, 6296, 7870, 15740, 31480.
What is 31480 in binary?
111101011111000 (hexadecimal 7AF8, octal 75370).
What is the square root of 31480?
About 177.4260, exactly 2√7870.
Is 31480 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 31480?
It is a composite number with 16 divisors.