The number 31388
31388 is a composite number with 24 divisors. Its prime factorisation is × 7 × 19 × 59. Divisors (24): 1, 2, 4, 7, 14, 19, 28, 38, 59, 76, 118, 133, 236, 266, 413, 532 … 31388.
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How to work it out
- 1
31388 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31388 is composite. Its prime factorisation is
- 3
The divisors add up to 67200; without 31388 itself that is 35812, so 31388 is abundant (35812 is more than 31388). Euler's totient φ(31388) = 12528 numbers up to 31388 share no factor with it.
- 4
The digits of 31388 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 129 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31388 = 2^{2} \times 7 \times 19 \times 59 \]31388 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 67200 |
| Euler totient φ(n) | 12528 |
| Square | 985206544 |
| Cube | 30923663003072 |
| Square root | 177.166588 (= 2√7847) |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 129 |
| Scientific notation | 3.1388 × |
31388 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and eighty-eight |
| Binary (base 2) | 111101010011100 |
| Octal (base 8) | 75234 |
| Hexadecimal (base 16) | 7A9C |
| Base 3 | 1121001112 |
| As time | 31388 seconds = 8 h 43 min 8 s |
Is 31388 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31388 ÷ 2 = 15694) | 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 (31388 ÷ 4 = 7847) | 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 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (31388 ÷ 7 = 4484) | 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 4) | 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 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 31388 a prime number?
No. 31388 = × 7 × 19 × 59, so it is divisible by 2.
What are the factors of 31388?
1, 2, 4, 7, 14, 19, 28, 38, 59, 76, 118, 133, 236, 266, 413, 532, 826, 1121, 1652, 2242, 4484, 7847, 15694, 31388.
What is 31388 in binary?
111101010011100 (hexadecimal 7A9C, octal 75234).
What is the square root of 31388?
About 177.1666, exactly 2√7847.
Is 31388 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 31388?
It is a composite number with 24 divisors.