The number 77842
77842 is a composite number with 4 divisors. Its prime factorisation is 2 × 38921. Divisors (4): 1, 2, 38921, 77842.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77842: a semiprime: 2 × 38921, the product of two primes.
- 2
77842 is composite. Its prime factorisation is
- 3
The divisors add up to 116766; without 77842 itself that is 38924, so 77842 is deficient (38924 is less than 77842). Euler's totient φ(77842) = 38920 numbers up to 77842 share no factor with it.
- 4
The digits of 77842 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 107 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77842 = 2 \times 38921 \]
77842 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 116766 |
| Euler totient φ(n) | 38920 |
| Square | 6059376964 |
| Cube | 471674021631688 |
| Square root | 279.001792 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 107 |
| Scientific notation | 7.7842 × |
77842 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand eight hundred and forty-two |
| Binary (base 2) | 10011000000010010 |
| Octal (base 8) | 230022 |
| Hexadecimal (base 16) | 13012 |
| Base 3 | 10221210001 |
| As time | 77842 seconds = 21 h 37 min 22 s |
Is 77842 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (77842 ÷ 2 = 38921) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 2) | 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 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 77842 a prime number?
No. 77842 = 2 × 38921, so it is divisible by 2.
What are the factors of 77842?
1, 2, 38921, 77842.
What is 77842 in binary?
10011000000010010 (hexadecimal 13012, octal 230022).
What is the square root of 77842?
About 279.0018.
Is 77842 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 77842?
77842 is a semiprime: 2 × 38921, the product of two primes.