The number 21026
21026 is a composite number with 4 divisors. Its prime factorisation is 2 × 10513. Divisors (4): 1, 2, 10513, 21026.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21026: a semiprime: 2 × 10513, the product of two primes.
- 2
21026 is composite. Its prime factorisation is
- 3
The divisors add up to 31542; without 21026 itself that is 10516, so 21026 is deficient (10516 is less than 21026). Euler's totient φ(21026) = 10512 numbers up to 21026 share no factor with it.
- 4
The digits of 21026 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 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21026 = 2 \times 10513 \]
21026 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 31542 |
| Euler totient φ(n) | 10512 |
| Square | 442092676 |
| Cube | 9295440605576 |
| Square root | 145.003448 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1026 × |
21026 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and twenty-six |
| Binary (base 2) | 101001000100010 |
| Octal (base 8) | 51042 |
| Hexadecimal (base 16) | 5222 |
| Base 3 | 1001211202 |
| As time | 21026 seconds = 5 h 50 min 26 s |
Is 21026 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21026 ÷ 2 = 10513) | 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 | No (remainder 1) | 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 2) | 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 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 21026 a prime number?
No. 21026 = 2 × 10513, so it is divisible by 2.
What are the factors of 21026?
1, 2, 10513, 21026.
What is 21026 in binary?
101001000100010 (hexadecimal 5222, octal 51042).
What is the square root of 21026?
About 145.0034.
Is 21026 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 21026?
21026 is a semiprime: 2 × 10513, the product of two primes.