The number 31129
31129 is a composite number with 4 divisors. Its prime factorisation is 7 × 4447. Divisors (4): 1, 7, 4447, 31129.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31129: a semiprime: 7 × 4447, the product of two primes.
- 2
31129 is composite. Its prime factorisation is
- 3
The divisors add up to 35584; without 31129 itself that is 4455, so 31129 is deficient (4455 is less than 31129). Euler's totient φ(31129) = 26676 numbers up to 31129 share no factor with it.
- 4
The digits of 31129 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 85 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31129 = 7 \times 4447 \]
31129 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 35584 |
| Euler totient φ(n) | 26676 |
| Square | 969014641 |
| Cube | 30164456759689 |
| Square root | 176.434124 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1129 × |
31129 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand one hundred and twenty-nine |
| Binary (base 2) | 111100110011001 |
| Octal (base 8) | 74631 |
| Hexadecimal (base 16) | 7999 |
| Base 3 | 1120200221 |
| As time | 31129 seconds = 8 h 38 min 49 s |
Is 31129 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 | Yes (31129 ÷ 7 = 4447) | 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 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 10) | 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 31129 a prime number?
No. 31129 = 7 × 4447, so it is divisible by 7.
What are the factors of 31129?
1, 7, 4447, 31129.
What is 31129 in binary?
111100110011001 (hexadecimal 7999, octal 74631).
What is the square root of 31129?
About 176.4341.
Is 31129 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 31129?
31129 is a semiprime: 7 × 4447, the product of two primes.