The number 31009
31009 is a composite number with 4 divisors. Its prime factorisation is 11 × 2819. Divisors (4): 1, 11, 2819, 31009.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31009: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 11 × 2819, the product of two primes.
- 2
31009 is composite. Its prime factorisation is
- 3
The divisors add up to 33840; without 31009 itself that is 2831, so 31009 is deficient (2831 is less than 31009). Euler's totient φ(31009) = 28180 numbers up to 31009 share no factor with it.
- 4
The digits of 31009 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31009 = 11 \times 2819 \]
31009 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 33840 |
| Euler totient φ(n) | 28180 |
| Square | 961558081 |
| Cube | 29816954533729 |
| Square root | 176.093725 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1009 × |
31009 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand and nine |
| Binary (base 2) | 111100100100001 |
| Octal (base 8) | 74441 |
| Hexadecimal (base 16) | 7921 |
| Base 3 | 1120112111 |
| As time | 31009 seconds = 8 h 36 min 49 s |
Is 31009 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 6) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | 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 | Yes (31009 ÷ 11 = 2819) | 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 31009 a prime number?
No. 31009 = 11 × 2819, so it is divisible by 11.
What are the factors of 31009?
1, 11, 2819, 31009.
What is 31009 in binary?
111100100100001 (hexadecimal 7921, octal 74441).
What is the square root of 31009?
About 176.0937.
Is 31009 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 31009?
31009 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 11 × 2819, the product of two primes.