The number 72421
72421 is the 7165th prime number. Its only divisors are 1 and 72421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 72421: the 7165th prime number.
- 2
72421 is prime, so its only factors are 1 and 72421. It is the 7165th prime; the next prime is 72431 and the one before is 72383.
- 3
The divisors add up to 72422; without 72421 itself that is 1, so 72421 is deficient (1 is less than 72421). Euler's totient φ(72421) = 72420 numbers up to 72421 share no factor with it.
- 4
The digits of 72421 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 42 steps to reach 1.
72421 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 72422 |
| Euler totient φ(n) | 72420 |
| Square | 5244801241 |
| Cube | 379833750674461 |
| Square root | 269.111501 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 42 |
| Scientific notation | 7.2421 × |
72421 in other forms
| Form | Value |
|---|---|
| In words | seventy-two thousand four hundred and twenty-one |
| Binary (base 2) | 10001101011100101 |
| Octal (base 8) | 215345 |
| Hexadecimal (base 16) | 11AE5 |
| Base 3 | 10200100021 |
| As time | 72421 seconds = 20 h 7 min 1 s |
Is 72421 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 6) | 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 8) | 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 72421 a prime number?
Yes. 72421 is divisible only by 1 and itself.
What are the factors of 72421?
1, 72421.
What is 72421 in binary?
10001101011100101 (hexadecimal 11AE5, octal 215345).
What is the square root of 72421?
About 269.1115.
Is 72421 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 72421?
72421 is the 7165th prime number.