The number 31309
31309 is a composite number with 4 divisors. Its prime factorisation is 131 × 239. Divisors (4): 1, 131, 239, 31309.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31309: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 131 × 239, the product of two primes.
- 2
31309 is composite. Its prime factorisation is
- 3
The divisors add up to 31680; without 31309 itself that is 371, so 31309 is deficient (371 is less than 31309). Euler's totient φ(31309) = 30940 numbers up to 31309 share no factor with it.
- 4
The digits of 31309 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 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31309 = 131 \times 239 \]
31309 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 31680 |
| Euler totient φ(n) | 30940 |
| Square | 980253481 |
| Cube | 30690756236629 |
| Square root | 176.943494 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.1309 × |
31309 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and nine |
| Binary (base 2) | 111101001001101 |
| Octal (base 8) | 75115 |
| Hexadecimal (base 16) | 7A4D |
| Base 3 | 1120221121 |
| As time | 31309 seconds = 8 h 41 min 49 s |
Is 31309 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 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 5) | 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 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31309 a prime number?
No. 31309 = 131 × 239, so it is divisible by 131.
What are the factors of 31309?
1, 131, 239, 31309.
What is 31309 in binary?
111101001001101 (hexadecimal 7A4D, octal 75115).
What is the square root of 31309?
About 176.9435.
Is 31309 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 31309?
31309 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 131 × 239, the product of two primes.