The number 77731
77731 is the 7641st prime number. Its only divisors are 1 and 77731.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77731: the 7641st prime number.
- 2
77731 is prime, so its only factors are 1 and 77731. It is the 7641st prime; the next prime is 77743 and the one before is 77723.
- 3
The divisors add up to 77732; without 77731 itself that is 1, so 77731 is deficient (1 is less than 77731). Euler's totient φ(77731) = 77730 numbers up to 77731 share no factor with it.
- 4
The digits of 77731 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 169 steps to reach 1.
77731 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 77732 |
| Euler totient φ(n) | 77730 |
| Square | 6042108361 |
| Cube | 469659125008891 |
| Square root | 278.802798 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 169 |
| Scientific notation | 7.7731 × |
77731 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand seven hundred and thirty-one |
| Binary (base 2) | 10010111110100011 |
| Octal (base 8) | 227643 |
| Hexadecimal (base 16) | 12FA3 |
| Base 3 | 10221121221 |
| As time | 77731 seconds = 21 h 35 min 31 s |
Is 77731 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 3) | 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 3) | 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 3) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 77731 a prime number?
Yes. 77731 is divisible only by 1 and itself.
What are the factors of 77731?
1, 77731.
What is 77731 in binary?
10010111110100011 (hexadecimal 12FA3, octal 227643).
What is the square root of 77731?
About 278.8028.
Is 77731 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 77731?
77731 is the 7641st prime number.