The number 31218
31218 is a composite number with 24 divisors. Its prime factorisation is 2 × 3 × × 43. Divisors (24): 1, 2, 3, 6, 11, 22, 33, 43, 66, 86, 121, 129, 242, 258, 363, 473 … 31218.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31218: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
31218 is composite. Its prime factorisation is
- 3
The divisors add up to 70224; without 31218 itself that is 39006, so 31218 is abundant (39006 is more than 31218). Euler's totient φ(31218) = 9240 numbers up to 31218 share no factor with it.
- 4
The digits of 31218 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31218 = 2 \times 3 \times 11^{2} \times 43 \]31218 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 70224 |
| Euler totient φ(n) | 9240 |
| Square | 974563524 |
| Cube | 30423924092232 |
| Square root | 176.686162 (= 11√258) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.1218 × |
31218 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and eighteen |
| Binary (base 2) | 111100111110010 |
| Octal (base 8) | 74762 |
| Hexadecimal (base 16) | 79F2 |
| Base 3 | 1120211020 |
| As time | 31218 seconds = 8 h 40 min 18 s |
Is 31218 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31218 ÷ 2 = 15609) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31218 ÷ 3 = 10406) | 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 (31218 ÷ 6 = 5203) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | 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 | Yes (31218 ÷ 11 = 2838) | 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 31218 a prime number?
No. 31218 = 2 × 3 × × 43, so it is divisible by 2.
What are the factors of 31218?
1, 2, 3, 6, 11, 22, 33, 43, 66, 86, 121, 129, 242, 258, 363, 473, 726, 946, 1419, 2838, 5203, 10406, 15609, 31218.
What is 31218 in binary?
111100111110010 (hexadecimal 79F2, octal 74762).
What is the square root of 31218?
About 176.6862, exactly 11√258.
Is 31218 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 31218?
31218 is a happy number: repeatedly adding the squares of its digits reaches 1.