The number 21071
21071 is a composite number with 4 divisors. Its prime factorisation is 19 × 1109. Divisors (4): 1, 19, 1109, 21071.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21071: a semiprime: 19 × 1109, the product of two primes.
- 2
21071 is composite. Its prime factorisation is
- 3
The divisors add up to 22200; without 21071 itself that is 1129, so 21071 is deficient (1129 is less than 21071). Euler's totient φ(21071) = 19944 numbers up to 21071 share no factor with it.
- 4
The digits of 21071 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21071 = 19 \times 1109 \]
21071 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22200 |
| Euler totient φ(n) | 19944 |
| Square | 443987041 |
| Cube | 9355250940911 |
| Square root | 145.158534 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1071 × |
21071 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and seventy-one |
| Binary (base 2) | 101001001001111 |
| Octal (base 8) | 51117 |
| Hexadecimal (base 16) | 524F |
| Base 3 | 1001220102 |
| As time | 21071 seconds = 5 h 51 min 11 s |
Is 21071 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | 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 3) | 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 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21071 a prime number?
No. 21071 = 19 × 1109, so it is divisible by 19.
What are the factors of 21071?
1, 19, 1109, 21071.
What is 21071 in binary?
101001001001111 (hexadecimal 524F, octal 51117).
What is the square root of 21071?
About 145.1585.
Is 21071 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 21071?
21071 is a semiprime: 19 × 1109, the product of two primes.