The number 31390
31390 is a composite number with 16 divisors. Its prime factorisation is 2 × 5 × 43 × 73. Divisors (16): 1, 2, 5, 10, 43, 73, 86, 146, 215, 365, 430, 730, 3139, 6278, 15695, 31390.
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How to work it out
- 1
What is special about 31390: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
31390 is composite. Its prime factorisation is
- 3
The divisors add up to 58608; without 31390 itself that is 27218, so 31390 is deficient (27218 is less than 31390). Euler's totient φ(31390) = 12096 numbers up to 31390 share no factor with it.
- 4
The digits of 31390 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 129 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31390 = 2 \times 5 \times 43 \times 73 \]
31390 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 58608 |
| Euler totient φ(n) | 12096 |
| Square | 985332100 |
| Cube | 30929574619000 |
| Square root | 177.172233 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 129 |
| Scientific notation | 3.139 × |
31390 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and ninety |
| Binary (base 2) | 111101010011110 |
| Octal (base 8) | 75236 |
| Hexadecimal (base 16) | 7A9E |
| Base 3 | 1121001121 |
| As time | 31390 seconds = 8 h 43 min 10 s |
Is 31390 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31390 ÷ 2 = 15695) | 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 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31390 ÷ 5 = 6278) | 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 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 | No (remainder 6) | 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 (31390 ÷ 10 = 3139) | 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 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31390 a prime number?
No. 31390 = 2 × 5 × 43 × 73, so it is divisible by 2.
What are the factors of 31390?
1, 2, 5, 10, 43, 73, 86, 146, 215, 365, 430, 730, 3139, 6278, 15695, 31390.
What is 31390 in binary?
111101010011110 (hexadecimal 7A9E, octal 75236).
What is the square root of 31390?
About 177.1722.
Is 31390 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 31390?
31390 is a happy number: repeatedly adding the squares of its digits reaches 1.