The number 2809
2809 is a perfect square (53²). Its prime factorisation is . Divisors (3): 1, 53, 2809.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 2809: a perfect square (53²); the square of a prime (53²).
- 2
2809 is composite. Its prime factorisation is
- 3
The divisors add up to 2863; without 2809 itself that is 54, so 2809 is deficient (54 is less than 2809). Euler's totient φ(2809) = 2756 numbers up to 2809 share no factor with it.
- 4
The digits of 2809 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 159 steps to reach 1.
LaTeX source of the formulas on this page
\[ 2809 = 53^{2} \]2809 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 3 |
| Sum of divisors | 2863 |
| Euler totient φ(n) | 2756 |
| Square | 7890481 |
| Cube | 22164361129 |
| Square root | 53 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 159 |
| Scientific notation | 2.809 × |
| Perfect power |
2809 in other forms
| Form | Value |
|---|---|
| In words | two thousand eight hundred and nine |
| Roman numerals | MMDCCCIX |
| Binary (base 2) | 101011111001 |
| Octal (base 8) | 5371 |
| Hexadecimal (base 16) | AF9 |
| Base 3 | 10212001 |
| As time | 2809 seconds = 46 min 49 s |
Is 2809 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 | No (remainder 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 | No (remainder 1) | 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 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 2809 a prime number?
No. 2809 = , so it is divisible by 53.
What are the factors of 2809?
1, 53, 2809.
What is 2809 in binary?
101011111001 (hexadecimal AF9, octal 5371).
What is the square root of 2809?
53, because 53 × 53 = 2809.
What is 2809 in Roman numerals?
MMDCCCIX.
Is 2809 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 2809?
2809 is a perfect square (53²); the square of a prime (53²).