The number 31311
31311 is a composite number with 18 divisors. Its prime factorisation is × × 71. Divisors (18): 1, 3, 7, 9, 21, 49, 63, 71, 147, 213, 441, 497, 639, 1491, 3479, 4473 … 31311.
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How to work it out
- 1
What is special about 31311: a Harshad number: divisible by its digit sum 9.
- 2
31311 is composite. Its prime factorisation is
- 3
The divisors add up to 53352; without 31311 itself that is 22041, so 31311 is deficient (22041 is less than 31311). Euler's totient φ(31311) = 17640 numbers up to 31311 share no factor with it.
- 4
The digits of 31311 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31311 = 3^{2} \times 7^{2} \times 71 \]31311 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 18 |
| Sum of divisors | 53352 |
| Euler totient φ(n) | 17640 |
| Square | 980378721 |
| Cube | 30696638133231 |
| Square root | 176.949145 (= 21√71) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1311 × |
31311 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and eleven |
| Binary (base 2) | 111101001001111 |
| Octal (base 8) | 75117 |
| Hexadecimal (base 16) | 7A4F |
| Base 3 | 1120221200 |
| As time | 31311 seconds = 8 h 41 min 51 s |
Is 31311 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31311 ÷ 3 = 10437) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (31311 ÷ 7 = 4473) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (31311 ÷ 9 = 3479) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31311 a prime number?
No. 31311 = × × 71, so it is divisible by 3.
What are the factors of 31311?
1, 3, 7, 9, 21, 49, 63, 71, 147, 213, 441, 497, 639, 1491, 3479, 4473, 10437, 31311.
What is 31311 in binary?
111101001001111 (hexadecimal 7A4F, octal 75117).
What is the square root of 31311?
About 176.9491, exactly 21√71.
Is 31311 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 31311?
31311 is a Harshad number: divisible by its digit sum 9.