The number 81424
81424 is a composite number with 20 divisors. Its prime factorisation is × 7 × 727. Divisors (20): 1, 2, 4, 7, 8, 14, 16, 28, 56, 112, 727, 1454, 2908, 5089, 5816, 10178 … 81424.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
81424 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81424 is composite. Its prime factorisation is
- 3
The divisors add up to 180544; without 81424 itself that is 99120, so 81424 is abundant (99120 is more than 81424). Euler's totient φ(81424) = 34848 numbers up to 81424 share no factor with it.
- 4
The digits of 81424 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 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81424 = 2^{4} \times 7 \times 727 \]81424 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 180544 |
| Euler totient φ(n) | 34848 |
| Square | 6629867776 |
| Cube | 539830353793024 |
| Square root | 285.348909 (= 4√5089) |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1424 × |
81424 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred and twenty-four |
| Binary (base 2) | 10011111000010000 |
| Octal (base 8) | 237020 |
| Hexadecimal (base 16) | 13E10 |
| Base 3 | 11010200201 |
| As time | 81424 seconds = 22 h 37 min 4 s |
Is 81424 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81424 ÷ 2 = 40712) | 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 | Yes (81424 ÷ 4 = 20356) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | 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 | Yes (81424 ÷ 7 = 11632) | 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 | Yes (81424 ÷ 8 = 10178) | 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 4) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81424 a prime number?
No. 81424 = × 7 × 727, so it is divisible by 2.
What are the factors of 81424?
1, 2, 4, 7, 8, 14, 16, 28, 56, 112, 727, 1454, 2908, 5089, 5816, 10178, 11632, 20356, 40712, 81424.
What is 81424 in binary?
10011111000010000 (hexadecimal 13E10, octal 237020).
What is the square root of 81424?
About 285.3489, exactly 4√5089.
Is 81424 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 81424?
It is a composite number with 20 divisors.