The number 21242
21242 is a composite number with 16 divisors. Its prime factorisation is 2 × 13 × 19 × 43. Divisors (16): 1, 2, 13, 19, 26, 38, 43, 86, 247, 494, 559, 817, 1118, 1634, 10621, 21242.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21242 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21242 is composite. Its prime factorisation is
- 3
The divisors add up to 36960; without 21242 itself that is 15718, so 21242 is deficient (15718 is less than 21242). Euler's totient φ(21242) = 9072 numbers up to 21242 share no factor with it.
- 4
The digits of 21242 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 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21242 = 2 \times 13 \times 19 \times 43 \]
21242 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 36960 |
| Euler totient φ(n) | 9072 |
| Square | 451222564 |
| Cube | 9584869704488 |
| Square root | 145.746355 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1242 × |
21242 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and forty-two |
| Binary (base 2) | 101001011111010 |
| Octal (base 8) | 51372 |
| Hexadecimal (base 16) | 52FA |
| Base 3 | 1002010202 |
| As time | 21242 seconds = 5 h 54 min 2 s |
Is 21242 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21242 ÷ 2 = 10621) | 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 2) | 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 4) | 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 2) | 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 21242 a prime number?
No. 21242 = 2 × 13 × 19 × 43, so it is divisible by 2.
What are the factors of 21242?
1, 2, 13, 19, 26, 38, 43, 86, 247, 494, 559, 817, 1118, 1634, 10621, 21242.
What is 21242 in binary?
101001011111010 (hexadecimal 52FA, octal 51372).
What is the square root of 21242?
About 145.7464.
Is 21242 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 21242?
It is a composite number with 16 divisors.