The number 390
390 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 5 × 13. Divisors (16): 1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 65, 78, 130, 195, 390.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
390 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
390 is composite. Its prime factorisation is
- 3
The divisors add up to 1008; without 390 itself that is 618, so 390 is abundant (618 is more than 390). Euler's totient φ(390) = 96 numbers up to 390 share no factor with it.
- 4
The digits of 390 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 390 = 2 \times 3 \times 5 \times 13 \]
390 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 1008 |
| Euler totient φ(n) | 96 |
| Square | 152100 |
| Cube | 59319000 |
| Square root | 19.748418 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 120 |
| Scientific notation | 3.9 × |
390 in other forms
| Form | Value |
|---|---|
| In words | three hundred and ninety |
| Roman numerals | CCCXC |
| Binary (base 2) | 110000110 |
| Octal (base 8) | 606 |
| Hexadecimal (base 16) | 186 |
| Base 3 | 112110 |
| As time | 390 seconds = 6 min 30 s |
Is 390 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (390 ÷ 2 = 195) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (390 ÷ 3 = 130) | 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 | Yes (390 ÷ 5 = 78) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (390 ÷ 6 = 65) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (390 ÷ 10 = 39) | 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 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 390 a prime number?
No. 390 = 2 × 3 × 5 × 13, so it is divisible by 2.
What are the factors of 390?
1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 65, 78, 130, 195, 390.
What is 390 in binary?
110000110 (hexadecimal 186, octal 606).
What is the square root of 390?
About 19.7484.
What is 390 in Roman numerals?
CCCXC.
Is 390 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 390?
It is a composite number with 16 divisors.