The number 21562
21562 is a composite number with 4 divisors. Its prime factorisation is 2 × 10781. Divisors (4): 1, 2, 10781, 21562.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21562: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10781, the product of two primes.
- 2
21562 is composite. Its prime factorisation is
- 3
The divisors add up to 32346; without 21562 itself that is 10784, so 21562 is deficient (10784 is less than 21562). Euler's totient φ(21562) = 10780 numbers up to 21562 share no factor with it.
- 4
The digits of 21562 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21562 = 2 \times 10781 \]
21562 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 32346 |
| Euler totient φ(n) | 10780 |
| Square | 464919844 |
| Cube | 10024601676328 |
| Square root | 146.840049 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1562 × |
21562 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and sixty-two |
| Binary (base 2) | 101010000111010 |
| Octal (base 8) | 52072 |
| Hexadecimal (base 16) | 543A |
| Base 3 | 1002120121 |
| As time | 21562 seconds = 5 h 59 min 22 s |
Is 21562 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21562 ÷ 2 = 10781) | 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 | No (remainder 2) | 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 | 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 2) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21562 a prime number?
No. 21562 = 2 × 10781, so it is divisible by 2.
What are the factors of 21562?
1, 2, 10781, 21562.
What is 21562 in binary?
101010000111010 (hexadecimal 543A, octal 52072).
What is the square root of 21562?
About 146.8400.
Is 21562 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21562?
21562 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10781, the product of two primes.