The number 80721
80721 is a composite number with 6 divisors. Its prime factorisation is × 8969. Divisors (6): 1, 3, 9, 8969, 26907, 80721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
80721 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
80721 is composite. Its prime factorisation is
- 3
The divisors add up to 116610; without 80721 itself that is 35889, so 80721 is deficient (35889 is less than 80721). Euler's totient φ(80721) = 53808 numbers up to 80721 share no factor with it.
- 4
The digits of 80721 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 107 steps to reach 1.
LaTeX source of the formulas on this page
\[ 80721 = 3^{2} \times 8969 \]80721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 116610 |
| Euler totient φ(n) | 53808 |
| Square | 6515879841 |
| Cube | 525968336645361 |
| Square root | 284.114414 (= 3√8969) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 107 |
| Scientific notation | 8.0721 × |
80721 in other forms
| Form | Value |
|---|---|
| In words | eighty thousand seven hundred and twenty-one |
| Binary (base 2) | 10011101101010001 |
| Octal (base 8) | 235521 |
| Hexadecimal (base 16) | 13B51 |
| Base 3 | 11002201200 |
| As time | 80721 seconds = 22 h 25 min 21 s |
Is 80721 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (80721 ÷ 3 = 26907) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (80721 ÷ 9 = 8969) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | 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 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 80721 a prime number?
No. 80721 = × 8969, so it is divisible by 3.
What are the factors of 80721?
1, 3, 9, 8969, 26907, 80721.
What is 80721 in binary?
10011101101010001 (hexadecimal 13B51, octal 235521).
What is the square root of 80721?
About 284.1144, exactly 3√8969.
Is 80721 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 80721?
It is a composite number with 6 divisors.