The number 81080
81080 is a composite number with 16 divisors. Its prime factorisation is × 5 × 2027. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 2027, 4054, 8108, 10135, 16216, 20270, 40540, 81080.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81080: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81080 is composite. Its prime factorisation is
- 3
The divisors add up to 182520; without 81080 itself that is 101440, so 81080 is abundant (101440 is more than 81080). Euler's totient φ(81080) = 32416 numbers up to 81080 share no factor with it.
- 4
The digits of 81080 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 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81080 = 2^{3} \times 5 \times 2027 \]81080 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 182520 |
| Euler totient φ(n) | 32416 |
| Square | 6573966400 |
| Cube | 533017195712000 |
| Square root | 284.745500 (= 2√20270) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.108 × |
81080 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand and eighty |
| Binary (base 2) | 10011110010111000 |
| Octal (base 8) | 236270 |
| Hexadecimal (base 16) | 13CB8 |
| Base 3 | 11010012222 |
| As time | 81080 seconds = 22 h 31 min 20 s |
Is 81080 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81080 ÷ 2 = 40540) | 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 | Yes (81080 ÷ 4 = 20270) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (81080 ÷ 5 = 16216) | 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 | No (remainder 6) | 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 (81080 ÷ 8 = 10135) | 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 | Yes (81080 ÷ 10 = 8108) | 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 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81080 a prime number?
No. 81080 = × 5 × 2027, so it is divisible by 2.
What are the factors of 81080?
1, 2, 4, 5, 8, 10, 20, 40, 2027, 4054, 8108, 10135, 16216, 20270, 40540, 81080.
What is 81080 in binary?
10011110010111000 (hexadecimal 13CB8, octal 236270).
What is the square root of 81080?
About 284.7455, exactly 2√20270.
Is 81080 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 81080?
81080 is a happy number: repeatedly adding the squares of its digits reaches 1.