The number 76821
76821 is a composite number with 8 divisors. Its prime factorisation is 3 × 29 × 883. Divisors (8): 1, 3, 29, 87, 883, 2649, 25607, 76821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
76821 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
76821 is composite. Its prime factorisation is
- 3
The divisors add up to 106080; without 76821 itself that is 29259, so 76821 is deficient (29259 is less than 76821). Euler's totient φ(76821) = 49392 numbers up to 76821 share no factor with it.
- 4
The digits of 76821 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 125 steps to reach 1.
LaTeX source of the formulas on this page
\[ 76821 = 3 \times 29 \times 883 \]
76821 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 106080 |
| Euler totient φ(n) | 49392 |
| Square | 5901466041 |
| Cube | 453356522735661 |
| Square root | 277.166015 |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 125 |
| Scientific notation | 7.6821 × |
76821 in other forms
| Form | Value |
|---|---|
| In words | seventy-six thousand eight hundred and twenty-one |
| Binary (base 2) | 10010110000010101 |
| Octal (base 8) | 226025 |
| Hexadecimal (base 16) | 12C15 |
| Base 3 | 10220101020 |
| As time | 76821 seconds = 21 h 20 min 21 s |
Is 76821 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 (76821 ÷ 3 = 25607) | 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 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | 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 8) | 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 76821 a prime number?
No. 76821 = 3 × 29 × 883, so it is divisible by 3.
What are the factors of 76821?
1, 3, 29, 87, 883, 2649, 25607, 76821.
What is 76821 in binary?
10010110000010101 (hexadecimal 12C15, octal 226025).
What is the square root of 76821?
About 277.1660.
Is 76821 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 76821?
It is a composite number with 8 divisors.