The number 1218
1218 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 7 × 29. Divisors (16): 1, 2, 3, 6, 7, 14, 21, 29, 42, 58, 87, 174, 203, 406, 609, 1218.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1218: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
1218 is composite. Its prime factorisation is
- 3
The divisors add up to 2880; without 1218 itself that is 1662, so 1218 is abundant (1662 is more than 1218). Euler's totient φ(1218) = 336 numbers up to 1218 share no factor with it.
- 4
The digits of 1218 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 132 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1218 = 2 \times 3 \times 7 \times 29 \]
1218 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 2880 |
| Euler totient φ(n) | 336 |
| Square | 1483524 |
| Cube | 1806932232 |
| Square root | 34.899857 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 132 |
| Scientific notation | 1.218 × |
1218 in other forms
| Form | Value |
|---|---|
| In words | one thousand two hundred and eighteen |
| Roman numerals | MCCXVIII |
| Binary (base 2) | 10011000010 |
| Octal (base 8) | 2302 |
| Hexadecimal (base 16) | 4C2 |
| Base 3 | 1200010 |
| As time | 1218 seconds = 20 min 18 s |
Is 1218 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (1218 ÷ 2 = 609) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (1218 ÷ 3 = 406) | 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 (1218 ÷ 6 = 203) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (1218 ÷ 7 = 174) | 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 8) | 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 1218 a prime number?
No. 1218 = 2 × 3 × 7 × 29, so it is divisible by 2.
What are the factors of 1218?
1, 2, 3, 6, 7, 14, 21, 29, 42, 58, 87, 174, 203, 406, 609, 1218.
What is 1218 in binary?
10011000010 (hexadecimal 4C2, octal 2302).
What is the square root of 1218?
About 34.8999.
What is 1218 in Roman numerals?
MCCXVIII.
Is 1218 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 1218?
1218 is a happy number: repeatedly adding the squares of its digits reaches 1.