The number 870
870 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 5 × 29. Divisors (16): 1, 2, 3, 5, 6, 10, 15, 29, 30, 58, 87, 145, 174, 290, 435, 870.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 870: a Harshad number: divisible by its digit sum 15.
- 2
870 is composite. Its prime factorisation is
- 3
The divisors add up to 2160; without 870 itself that is 1290, so 870 is abundant (1290 is more than 870). Euler's totient φ(870) = 224 numbers up to 870 share no factor with it.
- 4
The digits of 870 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 28 steps to reach 1.
LaTeX source of the formulas on this page
\[ 870 = 2 \times 3 \times 5 \times 29 \]
870 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 2160 |
| Euler totient φ(n) | 224 |
| Square | 756900 |
| Cube | 658503000 |
| Square root | 29.495762 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 28 |
| Scientific notation | 8.7 × |
870 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and seventy |
| Roman numerals | DCCCLXX |
| Binary (base 2) | 1101100110 |
| Octal (base 8) | 1546 |
| Hexadecimal (base 16) | 366 |
| Base 3 | 1012020 |
| As time | 870 seconds = 14 min 30 s |
Is 870 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (870 ÷ 2 = 435) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (870 ÷ 3 = 290) | 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 (870 ÷ 5 = 174) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (870 ÷ 6 = 145) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (870 ÷ 10 = 87) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 870 a prime number?
No. 870 = 2 × 3 × 5 × 29, so it is divisible by 2.
What are the factors of 870?
1, 2, 3, 5, 6, 10, 15, 29, 30, 58, 87, 145, 174, 290, 435, 870.
What is 870 in binary?
1101100110 (hexadecimal 366, octal 1546).
What is the square root of 870?
About 29.4958.
What is 870 in Roman numerals?
DCCCLXX.
Is 870 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 870?
870 is a Harshad number: divisible by its digit sum 15.