The number 81210
81210 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 5 × 2707. Divisors (16): 1, 2, 3, 5, 6, 10, 15, 30, 2707, 5414, 8121, 13535, 16242, 27070, 40605, 81210.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81210: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81210 is composite. Its prime factorisation is
- 3
The divisors add up to 194976; without 81210 itself that is 113766, so 81210 is abundant (113766 is more than 81210). Euler's totient φ(81210) = 21648 numbers up to 81210 share no factor with it.
- 4
The digits of 81210 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 151 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81210 = 2 \times 3 \times 5 \times 2707 \]
81210 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 194976 |
| Euler totient φ(n) | 21648 |
| Square | 6595064100 |
| Cube | 535585155561000 |
| Square root | 284.973683 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 151 |
| Scientific notation | 8.121 × |
81210 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and ten |
| Binary (base 2) | 10011110100111010 |
| Octal (base 8) | 236472 |
| Hexadecimal (base 16) | 13D3A |
| Base 3 | 11010101210 |
| As time | 81210 seconds = 22 h 33 min 30 s |
Is 81210 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81210 ÷ 2 = 40605) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81210 ÷ 3 = 27070) | 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 (81210 ÷ 5 = 16242) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (81210 ÷ 6 = 13535) | 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 2) | 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 (81210 ÷ 10 = 8121) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | 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 81210 a prime number?
No. 81210 = 2 × 3 × 5 × 2707, so it is divisible by 2.
What are the factors of 81210?
1, 2, 3, 5, 6, 10, 15, 30, 2707, 5414, 8121, 13535, 16242, 27070, 40605, 81210.
What is 81210 in binary?
10011110100111010 (hexadecimal 13D3A, octal 236472).
What is the square root of 81210?
About 284.9737.
Is 81210 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 81210?
81210 is a happy number: repeatedly adding the squares of its digits reaches 1.