The number 81480
81480 is a composite number with 64 divisors. Its prime factorisation is × 3 × 5 × 7 × 97. Divisors (64): 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28 … 81480.
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How to work it out
- 1
What is special about 81480: a Harshad number: divisible by its digit sum 21.
- 2
81480 is composite. Its prime factorisation is
- 3
The divisors add up to 282240; without 81480 itself that is 200760, so 81480 is abundant (200760 is more than 81480). Euler's totient φ(81480) = 18432 numbers up to 81480 share no factor with it.
- 4
The digits of 81480 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 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81480 = 2^{3} \times 3 \times 5 \times 7 \times 97 \]81480 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 64 |
| Sum of divisors | 282240 |
| Euler totient φ(n) | 18432 |
| Square | 6638990400 |
| Cube | 540944937792000 |
| Square root | 285.447018 (= 2√20370) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.148 × |
81480 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred and eighty |
| Binary (base 2) | 10011111001001000 |
| Octal (base 8) | 237110 |
| Hexadecimal (base 16) | 13E48 |
| Base 3 | 11010202210 |
| As time | 81480 seconds = 22 h 38 min 0 s |
Is 81480 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81480 ÷ 2 = 40740) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81480 ÷ 3 = 27160) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (81480 ÷ 4 = 20370) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (81480 ÷ 5 = 16296) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (81480 ÷ 6 = 13580) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (81480 ÷ 7 = 11640) | 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 (81480 ÷ 8 = 10185) | 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 | Yes (81480 ÷ 10 = 8148) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (81480 ÷ 12 = 6790) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81480 a prime number?
No. 81480 = × 3 × 5 × 7 × 97, so it is divisible by 2.
What are the factors of 81480?
1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 97, 105, 120, 140, 168, 194, 210, 280, 291, 388, 420, 485, 582, 679, 776, 840, 970, 1164, 1358, 1455, 1940, 2037, 2328, 2716, 2910, 3395, 3880, 4074, 5432, 5820, 6790, 8148, 10185, 11640, 13580, 16296, 20370, 27160, 40740, 81480.
What is 81480 in binary?
10011111001001000 (hexadecimal 13E48, octal 237110).
What is the square root of 81480?
About 285.4470, exactly 2√20370.
Is 81480 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 81480?
81480 is a Harshad number: divisible by its digit sum 21.