The number 1818
1818 is a composite number with 12 divisors. Its prime factorisation is 2 × × 101. Divisors (12): 1, 2, 3, 6, 9, 18, 101, 202, 303, 606, 909, 1818.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1818: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.
- 2
1818 is composite. Its prime factorisation is
- 3
The divisors add up to 3978; without 1818 itself that is 2160, so 1818 is abundant (2160 is more than 1818). Euler's totient φ(1818) = 600 numbers up to 1818 share no factor with it.
- 4
The digits of 1818 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 16 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1818 = 2 \times 3^{2} \times 101 \]1818 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 3978 |
| Euler totient φ(n) | 600 |
| Square | 3305124 |
| Cube | 6008715432 |
| Square root | 42.638011 (= 3√202) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 16 |
| Scientific notation | 1.818 × |
1818 in other forms
| Form | Value |
|---|---|
| In words | one thousand eight hundred and eighteen |
| Roman numerals | MDCCCXVIII |
| Binary (base 2) | 11100011010 |
| Octal (base 8) | 3432 |
| Hexadecimal (base 16) | 71A |
| Base 3 | 2111100 |
| As time | 1818 seconds = 30 min 18 s |
Is 1818 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (1818 ÷ 2 = 909) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (1818 ÷ 3 = 606) | 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 (1818 ÷ 6 = 303) | 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 | Yes (1818 ÷ 9 = 202) | 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 3) | 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 1818 a prime number?
No. 1818 = 2 × × 101, so it is divisible by 2.
What are the factors of 1818?
1, 2, 3, 6, 9, 18, 101, 202, 303, 606, 909, 1818.
What is 1818 in binary?
11100011010 (hexadecimal 71A, octal 3432).
What is the square root of 1818?
About 42.6380, exactly 3√202.
What is 1818 in Roman numerals?
MDCCCXVIII.
Is 1818 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 1818?
1818 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.