The number 3870
3870 is a composite number with 24 divisors. Its prime factorisation is 2 × × 5 × 43. Divisors (24): 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 43, 45, 86, 90, 129, 215 … 3870.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3870: a Harshad number: divisible by its digit sum 18.
- 2
3870 is composite. Its prime factorisation is
- 3
The divisors add up to 10296; without 3870 itself that is 6426, so 3870 is abundant (6426 is more than 3870). Euler's totient φ(3870) = 1008 numbers up to 3870 share no factor with it.
- 4
The digits of 3870 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 144 steps to reach 1.
LaTeX source of the formulas on this page
\[ 3870 = 2 \times 3^{2} \times 5 \times 43 \]3870 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 10296 |
| Euler totient φ(n) | 1008 |
| Square | 14976900 |
| Cube | 57960603000 |
| Square root | 62.209324 (= 3√430) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 144 |
| Scientific notation | 3.87 × |
3870 in other forms
| Form | Value |
|---|---|
| In words | three thousand eight hundred and seventy |
| Roman numerals | MMMDCCCLXX |
| Binary (base 2) | 111100011110 |
| Octal (base 8) | 7436 |
| Hexadecimal (base 16) | F1E |
| Base 3 | 12022100 |
| As time | 3870 seconds = 1 h 4 min 30 s |
Is 3870 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (3870 ÷ 2 = 1935) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (3870 ÷ 3 = 1290) | 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 (3870 ÷ 5 = 774) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (3870 ÷ 6 = 645) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 | Yes (3870 ÷ 9 = 430) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (3870 ÷ 10 = 387) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 3870 a prime number?
No. 3870 = 2 × × 5 × 43, so it is divisible by 2.
What are the factors of 3870?
1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 43, 45, 86, 90, 129, 215, 258, 387, 430, 645, 774, 1290, 1935, 3870.
What is 3870 in binary?
111100011110 (hexadecimal F1E, octal 7436).
What is the square root of 3870?
About 62.2093, exactly 3√430.
What is 3870 in Roman numerals?
MMMDCCCLXX.
Is 3870 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 3870?
3870 is a Harshad number: divisible by its digit sum 18.