The number 395
395 is a composite number with 4 divisors. Its prime factorisation is 5 × 79. Divisors (4): 1, 5, 79, 395.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 395: a semiprime: 5 × 79, the product of two primes.
- 2
395 is composite. Its prime factorisation is
- 3
The divisors add up to 480; without 395 itself that is 85, so 395 is deficient (85 is less than 395). Euler's totient φ(395) = 312 numbers up to 395 share no factor with it.
- 4
The digits of 395 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 76 steps to reach 1.
LaTeX source of the formulas on this page
\[ 395 = 5 \times 79 \]
395 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 480 |
| Euler totient φ(n) | 312 |
| Square | 156025 |
| Cube | 61629875 |
| Square root | 19.874607 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 76 |
| Scientific notation | 3.95 × |
395 in other forms
| Form | Value |
|---|---|
| In words | three hundred and ninety-five |
| Roman numerals | CCCXCV |
| Binary (base 2) | 110001011 |
| Octal (base 8) | 613 |
| Hexadecimal (base 16) | 18B |
| Base 3 | 112122 |
| As time | 395 seconds = 6 min 35 s |
Is 395 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 2) | 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 | Yes (395 ÷ 5 = 79) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | 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 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 395 a prime number?
No. 395 = 5 × 79, so it is divisible by 5.
What are the factors of 395?
1, 5, 79, 395.
What is 395 in binary?
110001011 (hexadecimal 18B, octal 613).
What is the square root of 395?
About 19.8746.
What is 395 in Roman numerals?
CCCXCV.
Is 395 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 395?
395 is a semiprime: 5 × 79, the product of two primes.