The number 77491
77491 is a twin prime (77489 and 77491 are both prime) and the 7613th prime number. Its only divisors are 1 and 77491.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77491: a twin prime (77489 and 77491 are both prime); the 7613th prime number.
- 2
77491 is prime, so its only factors are 1 and 77491. It is the 7613th prime; the next prime is 77509 and the one before is 77489.
- 3
The divisors add up to 77492; without 77491 itself that is 1, so 77491 is deficient (1 is less than 77491). Euler's totient φ(77491) = 77490 numbers up to 77491 share no factor with it.
- 4
The digits of 77491 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 169 steps to reach 1.
77491 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 77492 |
| Euler totient φ(n) | 77490 |
| Square | 6004855081 |
| Cube | 465322225081771 |
| Square root | 278.372053 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 169 |
| Scientific notation | 7.7491 × |
77491 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand four hundred and ninety-one |
| Binary (base 2) | 10010111010110011 |
| Octal (base 8) | 227263 |
| Hexadecimal (base 16) | 12EB3 |
| Base 3 | 10221022001 |
| As time | 77491 seconds = 21 h 31 min 31 s |
Is 77491 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 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 7) | 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 77491 a prime number?
Yes. 77491 is divisible only by 1 and itself.
What are the factors of 77491?
1, 77491.
What is 77491 in binary?
10010111010110011 (hexadecimal 12EB3, octal 227263).
What is the square root of 77491?
About 278.3721.
Is 77491 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 77491?
77491 is a twin prime (77489 and 77491 are both prime); the 7613th prime number.