The number 8821
8821 is a twin prime (8819 and 8821 are both prime) and the 1099th prime number. Its only divisors are 1 and 8821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 8821: a twin prime (8819 and 8821 are both prime); the 1099th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
8821 is prime, so its only factors are 1 and 8821. It is the 1099th prime; the next prime is 8831 and the one before is 8819.
- 3
The divisors add up to 8822; without 8821 itself that is 1, so 8821 is deficient (1 is less than 8821). Euler's totient φ(8821) = 8820 numbers up to 8821 share no factor with it.
- 4
The digits of 8821 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 47 steps to reach 1.
8821 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 8822 |
| Euler totient φ(n) | 8820 |
| Square | 77810041 |
| Cube | 686362371661 |
| Square root | 93.920179 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 47 |
| Scientific notation | 8.821 × |
8821 in other forms
| Form | Value |
|---|---|
| In words | eight thousand eight hundred and twenty-one |
| Binary (base 2) | 10001001110101 |
| Octal (base 8) | 21165 |
| Hexadecimal (base 16) | 2275 |
| Base 3 | 110002201 |
| As time | 8821 seconds = 2 h 27 min 1 s |
Is 8821 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 | No (remainder 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 1) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 8821 a prime number?
Yes. 8821 is divisible only by 1 and itself.
What are the factors of 8821?
1, 8821.
What is 8821 in binary?
10001001110101 (hexadecimal 2275, octal 21165).
What is the square root of 8821?
About 93.9202.
Is 8821 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 8821?
8821 is a twin prime (8819 and 8821 are both prime); the 1099th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.