The number 21996
21996 is a composite number with 36 divisors. Its prime factorisation is × × 13 × 47. Divisors (36): 1, 2, 3, 4, 6, 9, 12, 13, 18, 26, 36, 39, 47, 52, 78, 94 … 21996.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21996: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21996 is composite. Its prime factorisation is
- 3
The divisors add up to 61152; without 21996 itself that is 39156, so 21996 is abundant (39156 is more than 21996). Euler's totient φ(21996) = 6624 numbers up to 21996 share no factor with it.
- 4
The digits of 21996 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21996 = 2^{2} \times 3^{2} \times 13 \times 47 \]21996 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 36 |
| Sum of divisors | 61152 |
| Euler totient φ(n) | 6624 |
| Square | 483824016 |
| Cube | 10642193055936 |
| Square root | 148.310485 (= 6√611) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.1996 × |
21996 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and ninety-six |
| Binary (base 2) | 101010111101100 |
| Octal (base 8) | 52754 |
| Hexadecimal (base 16) | 55EC |
| Base 3 | 1010011200 |
| As time | 21996 seconds = 6 h 6 min 36 s |
Is 21996 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21996 ÷ 2 = 10998) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21996 ÷ 3 = 7332) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21996 ÷ 4 = 5499) | 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 (21996 ÷ 6 = 3666) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21996 ÷ 9 = 2444) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21996 ÷ 12 = 1833) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21996 a prime number?
No. 21996 = × × 13 × 47, so it is divisible by 2.
What are the factors of 21996?
1, 2, 3, 4, 6, 9, 12, 13, 18, 26, 36, 39, 47, 52, 78, 94, 117, 141, 156, 188, 234, 282, 423, 468, 564, 611, 846, 1222, 1692, 1833, 2444, 3666, 5499, 7332, 10998, 21996.
What is 21996 in binary?
101010111101100 (hexadecimal 55EC, octal 52754).
What is the square root of 21996?
About 148.3105, exactly 6√611.
Is 21996 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 21996?
21996 is a happy number: repeatedly adding the squares of its digits reaches 1.