The number 21396
21396 is a composite number with 12 divisors. Its prime factorisation is × 3 × 1783. Divisors (12): 1, 2, 3, 4, 6, 12, 1783, 3566, 5349, 7132, 10698, 21396.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21396 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21396 is composite. Its prime factorisation is
- 3
The divisors add up to 49952; without 21396 itself that is 28556, so 21396 is abundant (28556 is more than 21396). Euler's totient φ(21396) = 7128 numbers up to 21396 share no factor with it.
- 4
The digits of 21396 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21396 = 2^{2} \times 3 \times 1783 \]21396 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 49952 |
| Euler totient φ(n) | 7128 |
| Square | 457788816 |
| Cube | 9794849507136 |
| Square root | 146.273716 (= 2√5349) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1396 × |
21396 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and ninety-six |
| Binary (base 2) | 101001110010100 |
| Octal (base 8) | 51624 |
| Hexadecimal (base 16) | 5394 |
| Base 3 | 1002100110 |
| As time | 21396 seconds = 5 h 56 min 36 s |
Is 21396 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21396 ÷ 2 = 10698) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21396 ÷ 3 = 7132) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21396 ÷ 4 = 5349) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21396 ÷ 6 = 3566) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21396 ÷ 12 = 1783) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21396 a prime number?
No. 21396 = × 3 × 1783, so it is divisible by 2.
What are the factors of 21396?
1, 2, 3, 4, 6, 12, 1783, 3566, 5349, 7132, 10698, 21396.
What is 21396 in binary?
101001110010100 (hexadecimal 5394, octal 51624).
What is the square root of 21396?
About 146.2737, exactly 2√5349.
Is 21396 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 21396?
It is a composite number with 12 divisors.