The number 3920
3920 is a composite number with 30 divisors. Its prime factorisation is × 5 × . Divisors (30): 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70 … 3920.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3920: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 14.
- 2
3920 is composite. Its prime factorisation is
- 3
The divisors add up to 10602; without 3920 itself that is 6682, so 3920 is abundant (6682 is more than 3920). Euler's totient φ(3920) = 1344 numbers up to 3920 share no factor with it.
- 4
The digits of 3920 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 25 steps to reach 1.
LaTeX source of the formulas on this page
\[ 3920 = 2^{4} \times 5 \times 7^{2} \]3920 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 30 |
| Sum of divisors | 10602 |
| Euler totient φ(n) | 1344 |
| Square | 15366400 |
| Cube | 60236288000 |
| Square root | 62.609903 (= 28√5) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 25 |
| Scientific notation | 3.92 × |
3920 in other forms
| Form | Value |
|---|---|
| In words | three thousand nine hundred and twenty |
| Roman numerals | MMMCMXX |
| Binary (base 2) | 111101010000 |
| Octal (base 8) | 7520 |
| Hexadecimal (base 16) | F50 |
| Base 3 | 12101012 |
| As time | 3920 seconds = 1 h 5 min 20 s |
Is 3920 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (3920 ÷ 2 = 1960) | 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 | Yes (3920 ÷ 4 = 980) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (3920 ÷ 5 = 784) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (3920 ÷ 7 = 560) | 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 | Yes (3920 ÷ 8 = 490) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (3920 ÷ 10 = 392) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 3920 a prime number?
No. 3920 = × 5 × , so it is divisible by 2.
What are the factors of 3920?
1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960, 3920.
What is 3920 in binary?
111101010000 (hexadecimal F50, octal 7520).
What is the square root of 3920?
About 62.6099, exactly 28√5.
What is 3920 in Roman numerals?
MMMCMXX.
Is 3920 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 3920?
3920 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 14.