The number 81242
81242 is a composite number with 12 divisors. Its prime factorisation is 2 × × 829. Divisors (12): 1, 2, 7, 14, 49, 98, 829, 1658, 5803, 11606, 40621, 81242.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
81242 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81242 is composite. Its prime factorisation is
- 3
The divisors add up to 141930; without 81242 itself that is 60688, so 81242 is deficient (60688 is less than 81242). Euler's totient φ(81242) = 34776 numbers up to 81242 share no factor with it.
- 4
The digits of 81242 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81242 = 2 \times 7^{2} \times 829 \]81242 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 141930 |
| Euler totient φ(n) | 34776 |
| Square | 6600262564 |
| Cube | 536218531224488 |
| Square root | 285.029823 (= 7√1658) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1242 × |
81242 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and forty-two |
| Binary (base 2) | 10011110101011010 |
| Octal (base 8) | 236532 |
| Hexadecimal (base 16) | 13D5A |
| Base 3 | 11010102222 |
| As time | 81242 seconds = 22 h 34 min 2 s |
Is 81242 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81242 ÷ 2 = 40621) | 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 | Yes (81242 ÷ 7 = 11606) | 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 8) | 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 7) | 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 81242 a prime number?
No. 81242 = 2 × × 829, so it is divisible by 2.
What are the factors of 81242?
1, 2, 7, 14, 49, 98, 829, 1658, 5803, 11606, 40621, 81242.
What is 81242 in binary?
10011110101011010 (hexadecimal 13D5A, octal 236532).
What is the square root of 81242?
About 285.0298, exactly 7√1658.
Is 81242 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 81242?
It is a composite number with 12 divisors.