The number 5821
5821 is the 764th prime number. Its only divisors are 1 and 5821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 5821: the 764th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
5821 is prime, so its only factors are 1 and 5821. It is the 764th prime; the next prime is 5827 and the one before is 5813.
- 3
The divisors add up to 5822; without 5821 itself that is 1, so 5821 is deficient (1 is less than 5821). Euler's totient φ(5821) = 5820 numbers up to 5821 share no factor with it.
- 4
The digits of 5821 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 142 steps to reach 1.
5821 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 5822 |
| Euler totient φ(n) | 5820 |
| Square | 33884041 |
| Cube | 197239002661 |
| Square root | 76.295478 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 142 |
| Scientific notation | 5.821 × |
5821 in other forms
| Form | Value |
|---|---|
| In words | five thousand eight hundred and twenty-one |
| Binary (base 2) | 1011010111101 |
| Octal (base 8) | 13275 |
| Hexadecimal (base 16) | 16BD |
| Base 3 | 21222121 |
| As time | 5821 seconds = 1 h 37 min 1 s |
Is 5821 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 2) | 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 5821 a prime number?
Yes. 5821 is divisible only by 1 and itself.
What are the factors of 5821?
1, 5821.
What is 5821 in binary?
1011010111101 (hexadecimal 16BD, octal 13275).
What is the square root of 5821?
About 76.2955.
Is 5821 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 5821?
5821 is the 764th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.