The number 61381
61381 is a twin prime (61379 and 61381 are both prime) and the 6176th prime number. Its only divisors are 1 and 61381.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 61381: a twin prime (61379 and 61381 are both prime); the 6176th prime number.
- 2
61381 is prime, so its only factors are 1 and 61381. It is the 6176th prime; the next prime is 61403 and the one before is 61379.
- 3
The divisors add up to 61382; without 61381 itself that is 1, so 61381 is deficient (1 is less than 61381). Euler's totient φ(61381) = 61380 numbers up to 61381 share no factor with it.
- 4
The digits of 61381 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 60 steps to reach 1.
61381 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 61382 |
| Euler totient φ(n) | 61380 |
| Square | 3767627161 |
| Cube | 231260722769341 |
| Square root | 247.751892 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 60 |
| Scientific notation | 6.1381 × |
61381 in other forms
| Form | Value |
|---|---|
| In words | sixty-one thousand three hundred and eighty-one |
| Binary (base 2) | 1110111111000101 |
| Octal (base 8) | 167705 |
| Hexadecimal (base 16) | EFC5 |
| Base 3 | 10010012101 |
| As time | 61381 seconds = 17 h 3 min 1 s |
Is 61381 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 5) | 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 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 1) | 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 61381 a prime number?
Yes. 61381 is divisible only by 1 and itself.
What are the factors of 61381?
1, 61381.
What is 61381 in binary?
1110111111000101 (hexadecimal EFC5, octal 167705).
What is the square root of 61381?
About 247.7519.
Is 61381 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 61381?
61381 is a twin prime (61379 and 61381 are both prime); the 6176th prime number.