The number 12820
12820 is a composite number with 12 divisors. Its prime factorisation is × 5 × 641. Divisors (12): 1, 2, 4, 5, 10, 20, 641, 1282, 2564, 3205, 6410, 12820.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
12820 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
12820 is composite. Its prime factorisation is
- 3
The divisors add up to 26964; without 12820 itself that is 14144, so 12820 is abundant (14144 is more than 12820). Euler's totient φ(12820) = 5120 numbers up to 12820 share no factor with it.
- 4
The digits of 12820 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 63 steps to reach 1.
LaTeX source of the formulas on this page
\[ 12820 = 2^{2} \times 5 \times 641 \]12820 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 26964 |
| Euler totient φ(n) | 5120 |
| Square | 164352400 |
| Cube | 2106997768000 |
| Square root | 113.225439 (= 2√3205) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 63 |
| Scientific notation | 1.282 × |
12820 in other forms
| Form | Value |
|---|---|
| In words | twelve thousand eight hundred and twenty |
| Binary (base 2) | 11001000010100 |
| Octal (base 8) | 31024 |
| Hexadecimal (base 16) | 3214 |
| Base 3 | 122120211 |
| As time | 12820 seconds = 3 h 33 min 40 s |
Is 12820 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (12820 ÷ 2 = 6410) | 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 | Yes (12820 ÷ 4 = 3205) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (12820 ÷ 5 = 2564) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (12820 ÷ 10 = 1282) | 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 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 12820 a prime number?
No. 12820 = × 5 × 641, so it is divisible by 2.
What are the factors of 12820?
1, 2, 4, 5, 10, 20, 641, 1282, 2564, 3205, 6410, 12820.
What is 12820 in binary?
11001000010100 (hexadecimal 3214, octal 31024).
What is the square root of 12820?
About 113.2254, exactly 2√3205.
Is 12820 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 12820?
It is a composite number with 12 divisors.