The number 21110
21110 is a composite number with 8 divisors. Its prime factorisation is 2 × 5 × 2111. Divisors (8): 1, 2, 5, 10, 2111, 4222, 10555, 21110.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21110: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 5.
- 2
21110 is composite. Its prime factorisation is
- 3
The divisors add up to 38016; without 21110 itself that is 16906, so 21110 is deficient (16906 is less than 21110). Euler's totient φ(21110) = 8440 numbers up to 21110 share no factor with it.
- 4
The digits of 21110 add up to 5, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21110 = 2 \times 5 \times 2111 \]
21110 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 38016 |
| Euler totient φ(n) | 8440 |
| Square | 445632100 |
| Cube | 9407293631000 |
| Square root | 145.292808 |
| Digit sum / digital root | 5 / 5 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.111 × |
21110 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and ten |
| Binary (base 2) | 101001001110110 |
| Octal (base 8) | 51166 |
| Hexadecimal (base 16) | 5276 |
| Base 3 | 1001221212 |
| As time | 21110 seconds = 5 h 51 min 50 s |
Is 21110 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21110 ÷ 2 = 10555) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21110 ÷ 5 = 4222) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21110 ÷ 10 = 2111) | 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 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21110 a prime number?
No. 21110 = 2 × 5 × 2111, so it is divisible by 2.
What are the factors of 21110?
1, 2, 5, 10, 2111, 4222, 10555, 21110.
What is 21110 in binary?
101001001110110 (hexadecimal 5276, octal 51166).
What is the square root of 21110?
About 145.2928.
Is 21110 divisible by 3?
No. Its digits add up to 5, which is not a multiple of 3.
What is special about the number 21110?
21110 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 5.