The number 72221
72221 is a twin prime (72221 and 72223 are both prime) and the 7147th prime number. Its only divisors are 1 and 72221.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 72221: a twin prime (72221 and 72223 are both prime); the 7147th prime number.
- 2
72221 is prime, so its only factors are 1 and 72221. It is the 7147th prime; the next prime is 72223 and the one before is 72211.
- 3
The divisors add up to 72222; without 72221 itself that is 1, so 72221 is deficient (1 is less than 72221). Euler's totient φ(72221) = 72220 numbers up to 72221 share no factor with it.
- 4
The digits of 72221 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 187 steps to reach 1.
72221 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 72222 |
| Euler totient φ(n) | 72220 |
| Square | 5215872841 |
| Cube | 376695552449861 |
| Square root | 268.739651 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 187 |
| Scientific notation | 7.2221 × |
72221 in other forms
| Form | Value |
|---|---|
| In words | seventy-two thousand two hundred and twenty-one |
| Binary (base 2) | 10001101000011101 |
| Octal (base 8) | 215035 |
| Hexadecimal (base 16) | 11A1D |
| Base 3 | 10200001212 |
| As time | 72221 seconds = 20 h 3 min 41 s |
Is 72221 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 2) | 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 5) | 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 6) | 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 72221 a prime number?
Yes. 72221 is divisible only by 1 and itself.
What are the factors of 72221?
1, 72221.
What is 72221 in binary?
10001101000011101 (hexadecimal 11A1D, octal 215035).
What is the square root of 72221?
About 268.7397.
Is 72221 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 72221?
72221 is a twin prime (72221 and 72223 are both prime); the 7147th prime number.