The number 21112
21112 is a palindrome: it reads 21112 backwards too. Its prime factorisation is × 7 × 13 × 29. Divisors (32): 1, 2, 4, 7, 8, 13, 14, 26, 28, 29, 52, 56, 58, 91, 104, 116 … 21112.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21112: a palindrome: it reads 21112 backwards too; a Harshad number: divisible by its digit sum 7.
- 2
21112 is composite. Its prime factorisation is
- 3
The divisors add up to 50400; without 21112 itself that is 29288, so 21112 is abundant (29288 is more than 21112). Euler's totient φ(21112) = 8064 numbers up to 21112 share no factor with it.
- 4
The digits of 21112 add up to 7, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21112 = 2^{3} \times 7 \times 13 \times 29 \]21112 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 50400 |
| Euler totient φ(n) | 8064 |
| Square | 445716544 |
| Cube | 9409967676928 |
| Square root | 145.299690 (= 2√5278) |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.1112 × |
21112 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and twelve |
| Binary (base 2) | 101001001111000 |
| Octal (base 8) | 51170 |
| Hexadecimal (base 16) | 5278 |
| Base 3 | 1001221221 |
| As time | 21112 seconds = 5 h 51 min 52 s |
Is 21112 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21112 ÷ 2 = 10556) | 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 (21112 ÷ 4 = 5278) | 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 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21112 ÷ 7 = 3016) | 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 | Yes (21112 ÷ 8 = 2639) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 3) | 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 21112 a prime number?
No. 21112 = × 7 × 13 × 29, so it is divisible by 2.
What are the factors of 21112?
1, 2, 4, 7, 8, 13, 14, 26, 28, 29, 52, 56, 58, 91, 104, 116, 182, 203, 232, 364, 377, 406, 728, 754, 812, 1508, 1624, 2639, 3016, 5278, 10556, 21112.
What is 21112 in binary?
101001001111000 (hexadecimal 5278, octal 51170).
What is the square root of 21112?
About 145.2997, exactly 2√5278.
Is 21112 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 21112?
21112 is a palindrome: it reads 21112 backwards too; a Harshad number: divisible by its digit sum 7.