The number 1809
1809 is a composite number with 8 divisors. Its prime factorisation is × 67. Divisors (8): 1, 3, 9, 27, 67, 201, 603, 1809.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
1809 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
1809 is composite. Its prime factorisation is
- 3
The divisors add up to 2720; without 1809 itself that is 911, so 1809 is deficient (911 is less than 1809). Euler's totient φ(1809) = 1188 numbers up to 1809 share no factor with it.
- 4
The digits of 1809 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 55 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1809 = 3^{3} \times 67 \]1809 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 2720 |
| Euler totient φ(n) | 1188 |
| Square | 3272481 |
| Cube | 5919918129 |
| Square root | 42.532341 (= 3√201) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 55 |
| Scientific notation | 1.809 × |
1809 in other forms
| Form | Value |
|---|---|
| In words | one thousand eight hundred and nine |
| Roman numerals | MDCCCIX |
| Binary (base 2) | 11100010001 |
| Octal (base 8) | 3421 |
| Hexadecimal (base 16) | 711 |
| Base 3 | 2111000 |
| As time | 1809 seconds = 30 min 9 s |
Is 1809 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (1809 ÷ 3 = 603) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (1809 ÷ 9 = 201) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1809 a prime number?
No. 1809 = × 67, so it is divisible by 3.
What are the factors of 1809?
1, 3, 9, 27, 67, 201, 603, 1809.
What is 1809 in binary?
11100010001 (hexadecimal 711, octal 3421).
What is the square root of 1809?
About 42.5323, exactly 3√201.
What is 1809 in Roman numerals?
MDCCCIX.
Is 1809 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 1809?
It is a composite number with 8 divisors.