The number 81642
81642 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 11 × 1237. Divisors (16): 1, 2, 3, 6, 11, 22, 33, 66, 1237, 2474, 3711, 7422, 13607, 27214, 40821, 81642.
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How to work it out
- 1
81642 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81642 is composite. Its prime factorisation is
- 3
The divisors add up to 178272; without 81642 itself that is 96630, so 81642 is abundant (96630 is more than 81642). Euler's totient φ(81642) = 24720 numbers up to 81642 share no factor with it.
- 4
The digits of 81642 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81642 = 2 \times 3 \times 11 \times 1237 \]
81642 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 178272 |
| Euler totient φ(n) | 24720 |
| Square | 6665416164 |
| Cube | 544177906461288 |
| Square root | 285.730642 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1642 × |
81642 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand six hundred and forty-two |
| Binary (base 2) | 10011111011101010 |
| Octal (base 8) | 237352 |
| Hexadecimal (base 16) | 13EEA |
| Base 3 | 11010222210 |
| As time | 81642 seconds = 22 h 40 min 42 s |
Is 81642 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81642 ÷ 2 = 40821) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81642 ÷ 3 = 27214) | 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 (81642 ÷ 6 = 13607) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 | Yes (81642 ÷ 11 = 7422) | 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 81642 a prime number?
No. 81642 = 2 × 3 × 11 × 1237, so it is divisible by 2.
What are the factors of 81642?
1, 2, 3, 6, 11, 22, 33, 66, 1237, 2474, 3711, 7422, 13607, 27214, 40821, 81642.
What is 81642 in binary?
10011111011101010 (hexadecimal 13EEA, octal 237352).
What is the square root of 81642?
About 285.7306.
Is 81642 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 81642?
It is a composite number with 16 divisors.