The number 218
218 is a composite number with 4 divisors. Its prime factorisation is 2 × 109. Divisors (4): 1, 2, 109, 218.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 218: a semiprime: 2 × 109, the product of two primes.
- 2
218 is composite. Its prime factorisation is
- 3
The divisors add up to 330; without 218 itself that is 112, so 218 is deficient (112 is less than 218). Euler's totient φ(218) = 108 numbers up to 218 share no factor with it.
- 4
The digits of 218 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 114 steps to reach 1.
LaTeX source of the formulas on this page
\[ 218 = 2 \times 109 \]
218 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 330 |
| Euler totient φ(n) | 108 |
| Square | 47524 |
| Cube | 10360232 |
| Square root | 14.764823 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 114 |
| Scientific notation | 2.18 × |
218 in other forms
| Form | Value |
|---|---|
| In words | two hundred and eighteen |
| Roman numerals | CCXVIII |
| Binary (base 2) | 11011010 |
| Octal (base 8) | 332 |
| Hexadecimal (base 16) | DA |
| Base 3 | 22002 |
| As time | 218 seconds = 3 min 38 s |
Is 218 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (218 ÷ 2 = 109) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | 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 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 2) | 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 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 218 a prime number?
No. 218 = 2 × 109, so it is divisible by 2.
What are the factors of 218?
1, 2, 109, 218.
What is 218 in binary?
11011010 (hexadecimal DA, octal 332).
What is the square root of 218?
About 14.7648.
What is 218 in Roman numerals?
CCXVIII.
Is 218 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 218?
218 is a semiprime: 2 × 109, the product of two primes.