The number 21612
21612 is a palindrome: it reads 21612 backwards too. Its prime factorisation is × 3 × 1801. Divisors (12): 1, 2, 3, 4, 6, 12, 1801, 3602, 5403, 7204, 10806, 21612.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21612: a palindrome: it reads 21612 backwards too; a Harshad number: divisible by its digit sum 12.
- 2
21612 is composite. Its prime factorisation is
- 3
The divisors add up to 50456; without 21612 itself that is 28844, so 21612 is abundant (28844 is more than 21612). Euler's totient φ(21612) = 7200 numbers up to 21612 share no factor with it.
- 4
The digits of 21612 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21612 = 2^{2} \times 3 \times 1801 \]21612 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 50456 |
| Euler totient φ(n) | 7200 |
| Square | 467078544 |
| Cube | 10094501492928 |
| Square root | 147.010204 (= 2√5403) |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.1612 × |
21612 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and twelve |
| Binary (base 2) | 101010001101100 |
| Octal (base 8) | 52154 |
| Hexadecimal (base 16) | 546C |
| Base 3 | 1002122110 |
| As time | 21612 seconds = 6 h 0 min 12 s |
Is 21612 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21612 ÷ 2 = 10806) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21612 ÷ 3 = 7204) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21612 ÷ 4 = 5403) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21612 ÷ 6 = 3602) | 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 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21612 ÷ 12 = 1801) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21612 a prime number?
No. 21612 = × 3 × 1801, so it is divisible by 2.
What are the factors of 21612?
1, 2, 3, 4, 6, 12, 1801, 3602, 5403, 7204, 10806, 21612.
What is 21612 in binary?
101010001101100 (hexadecimal 546C, octal 52154).
What is the square root of 21612?
About 147.0102, exactly 2√5403.
Is 21612 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21612?
21612 is a palindrome: it reads 21612 backwards too; a Harshad number: divisible by its digit sum 12.