The number 73721
73721 is the 7280th prime number. Its only divisors are 1 and 73721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 73721: the 7280th prime number.
- 2
73721 is prime, so its only factors are 1 and 73721. It is the 7280th prime; the next prime is 73727 and the one before is 73709.
- 3
The divisors add up to 73722; without 73721 itself that is 1, so 73721 is deficient (1 is less than 73721). Euler's totient φ(73721) = 73720 numbers up to 73721 share no factor with it.
- 4
The digits of 73721 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 156 steps to reach 1.
73721 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 73722 |
| Euler totient φ(n) | 73720 |
| Square | 5434785841 |
| Cube | 400657846984361 |
| Square root | 271.516114 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 156 |
| Scientific notation | 7.3721 × |
73721 in other forms
| Form | Value |
|---|---|
| In words | seventy-three thousand seven hundred and twenty-one |
| Binary (base 2) | 10001111111111001 |
| Octal (base 8) | 217771 |
| Hexadecimal (base 16) | 11FF9 |
| Base 3 | 10202010102 |
| As time | 73721 seconds = 20 h 28 min 41 s |
Is 73721 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 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 1) | 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 10) | 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 73721 a prime number?
Yes. 73721 is divisible only by 1 and itself.
What are the factors of 73721?
1, 73721.
What is 73721 in binary?
10001111111111001 (hexadecimal 11FF9, octal 217771).
What is the square root of 73721?
About 271.5161.
Is 73721 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 73721?
73721 is the 7280th prime number.