The number 80640
80640 is a composite number with 108 divisors. Its prime factorisation is × × 5 × 7. Divisors (108): 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20 … 80640.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 80640: a Harshad number: divisible by its digit sum 18.
- 2
80640 is composite. Its prime factorisation is
- 3
The divisors add up to 318864; without 80640 itself that is 238224, so 80640 is abundant (238224 is more than 80640). Euler's totient φ(80640) = 18432 numbers up to 80640 share no factor with it.
- 4
The digits of 80640 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 45 steps to reach 1.
LaTeX source of the formulas on this page
\[ 80640 = 2^{8} \times 3^{2} \times 5 \times 7 \]80640 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 108 |
| Sum of divisors | 318864 |
| Euler totient φ(n) | 18432 |
| Square | 6502809600 |
| Cube | 524386566144000 |
| Square root | 283.971830 (= 48√35) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 45 |
| Scientific notation | 8.064 × |
80640 in other forms
| Form | Value |
|---|---|
| In words | eighty thousand six hundred and forty |
| Binary (base 2) | 10011101100000000 |
| Octal (base 8) | 235400 |
| Hexadecimal (base 16) | 13B00 |
| Base 3 | 11002121200 |
| As time | 80640 seconds = 22 h 24 min 0 s |
Is 80640 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (80640 ÷ 2 = 40320) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (80640 ÷ 3 = 26880) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (80640 ÷ 4 = 20160) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (80640 ÷ 5 = 16128) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (80640 ÷ 6 = 13440) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (80640 ÷ 7 = 11520) | 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 (80640 ÷ 8 = 10080) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (80640 ÷ 9 = 8960) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (80640 ÷ 10 = 8064) | 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 | Yes (80640 ÷ 12 = 6720) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 80640 a prime number?
No. 80640 = × × 5 × 7, so it is divisible by 2.
What are the factors of 80640?
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 32, 35, 36, 40, 42, 45, 48, 56, 60, 63, 64, 70, 72, 80, 84, 90, 96, 105, 112, 120, 126, 128, 140, 144, 160, 168, 180, 192, 210, 224, 240, 252, 256, 280, 288, 315, 320, 336, 360, 384, 420, 448, 480, 504, 560, 576, 630, 640, 672, 720, 768, 840, 896, 960, 1008, 1120, 1152, 1260, 1280, 1344, 1440, 1680, 1792, 1920, 2016, 2240, 2304, 2520, 2688, 2880, 3360, 3840, 4032, 4480, 5040, 5376, 5760, 6720, 8064, 8960, 10080, 11520, 13440, 16128, 20160, 26880, 40320, 80640.
What is 80640 in binary?
10011101100000000 (hexadecimal 13B00, octal 235400).
What is the square root of 80640?
About 283.9718, exactly 48√35.
Is 80640 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 80640?
80640 is a Harshad number: divisible by its digit sum 18.