The number 21358
21358 is a composite number with 8 divisors. Its prime factorisation is 2 × 59 × 181. Divisors (8): 1, 2, 59, 118, 181, 362, 10679, 21358.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21358: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21358 is composite. Its prime factorisation is
- 3
The divisors add up to 32760; without 21358 itself that is 11402, so 21358 is deficient (11402 is less than 21358). Euler's totient φ(21358) = 10440 numbers up to 21358 share no factor with it.
- 4
The digits of 21358 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21358 = 2 \times 59 \times 181 \]
21358 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 32760 |
| Euler totient φ(n) | 10440 |
| Square | 456164164 |
| Cube | 9742754214712 |
| Square root | 146.143765 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1358 × |
21358 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and fifty-eight |
| Binary (base 2) | 101001101101110 |
| Octal (base 8) | 51556 |
| Hexadecimal (base 16) | 536E |
| Base 3 | 1002022001 |
| As time | 21358 seconds = 5 h 55 min 58 s |
Is 21358 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21358 ÷ 2 = 10679) | 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 3) | 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 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 21358 a prime number?
No. 21358 = 2 × 59 × 181, so it is divisible by 2.
What are the factors of 21358?
1, 2, 59, 118, 181, 362, 10679, 21358.
What is 21358 in binary?
101001101101110 (hexadecimal 536E, octal 51556).
What is the square root of 21358?
About 146.1438.
Is 21358 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 21358?
21358 is a happy number: repeatedly adding the squares of its digits reaches 1.