The number 87221
87221 is a twin prime (87221 and 87223 are both prime) and the 8469th prime number. Its only divisors are 1 and 87221.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 87221: a twin prime (87221 and 87223 are both prime); the 8469th prime number.
- 2
87221 is prime, so its only factors are 1 and 87221. It is the 8469th prime; the next prime is 87223 and the one before is 87211.
- 3
The divisors add up to 87222; without 87221 itself that is 1, so 87221 is deficient (1 is less than 87221). Euler's totient φ(87221) = 87220 numbers up to 87221 share no factor with it.
- 4
The digits of 87221 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 58 steps to reach 1.
87221 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 87222 |
| Euler totient φ(n) | 87220 |
| Square | 7607502841 |
| Cube | 663534005294861 |
| Square root | 295.332017 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 58 |
| Scientific notation | 8.7221 × |
87221 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand two hundred and twenty-one |
| Binary (base 2) | 10101010010110101 |
| Octal (base 8) | 252265 |
| Hexadecimal (base 16) | 154B5 |
| Base 3 | 11102122102 |
| As time | 87221 seconds = 24 h 13 min 41 s |
Is 87221 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 2) | 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 5) | 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 2) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87221 a prime number?
Yes. 87221 is divisible only by 1 and itself.
What are the factors of 87221?
1, 87221.
What is 87221 in binary?
10101010010110101 (hexadecimal 154B5, octal 252265).
What is the square root of 87221?
About 295.3320.
Is 87221 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 87221?
87221 is a twin prime (87221 and 87223 are both prime); the 8469th prime number.