The number 21042
21042 is a composite number with 24 divisors. Its prime factorisation is 2 × × 7 × 167. Divisors (24): 1, 2, 3, 6, 7, 9, 14, 18, 21, 42, 63, 126, 167, 334, 501, 1002 … 21042.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21042: a Harshad number: divisible by its digit sum 9.
- 2
21042 is composite. Its prime factorisation is
- 3
The divisors add up to 52416; without 21042 itself that is 31374, so 21042 is abundant (31374 is more than 21042). Euler's totient φ(21042) = 5976 numbers up to 21042 share no factor with it.
- 4
The digits of 21042 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 105 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21042 = 2 \times 3^{2} \times 7 \times 167 \]21042 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 52416 |
| Euler totient φ(n) | 5976 |
| Square | 442765764 |
| Cube | 9316677206088 |
| Square root | 145.058609 (= 3√2338) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 105 |
| Scientific notation | 2.1042 × |
21042 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and forty-two |
| Binary (base 2) | 101001000110010 |
| Octal (base 8) | 51062 |
| Hexadecimal (base 16) | 5232 |
| Base 3 | 1001212100 |
| As time | 21042 seconds = 5 h 50 min 42 s |
Is 21042 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21042 ÷ 2 = 10521) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21042 ÷ 3 = 7014) | 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 | Yes (21042 ÷ 6 = 3507) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21042 ÷ 7 = 3006) | 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 | Yes (21042 ÷ 9 = 2338) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21042 a prime number?
No. 21042 = 2 × × 7 × 167, so it is divisible by 2.
What are the factors of 21042?
1, 2, 3, 6, 7, 9, 14, 18, 21, 42, 63, 126, 167, 334, 501, 1002, 1169, 1503, 2338, 3006, 3507, 7014, 10521, 21042.
What is 21042 in binary?
101001000110010 (hexadecimal 5232, octal 51062).
What is the square root of 21042?
About 145.0586, exactly 3√2338.
Is 21042 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 21042?
21042 is a Harshad number: divisible by its digit sum 9.