The number 31818
31818 is a composite number with 8 divisors. Its prime factorisation is 2 × 3 × 5303. Divisors (8): 1, 2, 3, 6, 5303, 10606, 15909, 31818.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31818: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
31818 is composite. Its prime factorisation is
- 3
The divisors add up to 63648; without 31818 itself that is 31830, so 31818 is abundant (31830 is more than 31818). Euler's totient φ(31818) = 10604 numbers up to 31818 share no factor with it.
- 4
The digits of 31818 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31818 = 2 \times 3 \times 5303 \]
31818 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 63648 |
| Euler totient φ(n) | 10604 |
| Square | 1012385124 |
| Cube | 32212069875432 |
| Square root | 178.376007 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.1818 × |
31818 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and eighteen |
| Binary (base 2) | 111110001001010 |
| Octal (base 8) | 76112 |
| Hexadecimal (base 16) | 7C4A |
| Base 3 | 1121122110 |
| As time | 31818 seconds = 8 h 50 min 18 s |
Is 31818 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31818 ÷ 2 = 15909) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31818 ÷ 3 = 10606) | 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 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (31818 ÷ 6 = 5303) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31818 a prime number?
No. 31818 = 2 × 3 × 5303, so it is divisible by 2.
What are the factors of 31818?
1, 2, 3, 6, 5303, 10606, 15909, 31818.
What is 31818 in binary?
111110001001010 (hexadecimal 7C4A, octal 76112).
What is the square root of 31818?
About 178.3760.
Is 31818 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 31818?
31818 is a happy number: repeatedly adding the squares of its digits reaches 1.