The number 81250
81250 is a composite number with 24 divisors. Its prime factorisation is 2 × × 13. Divisors (24): 1, 2, 5, 10, 13, 25, 26, 50, 65, 125, 130, 250, 325, 625, 650, 1250 … 81250.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81250: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81250 is composite. Its prime factorisation is
- 3
The divisors add up to 164052; without 81250 itself that is 82802, so 81250 is abundant (82802 is more than 81250). Euler's totient φ(81250) = 30000 numbers up to 81250 share no factor with it.
- 4
The digits of 81250 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 182 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81250 = 2 \times 5^{5} \times 13 \]81250 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 164052 |
| Euler totient φ(n) | 30000 |
| Square | 6601562500 |
| Cube | 536376953125000 |
| Square root | 285.043856 (= 25√130) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 182 |
| Scientific notation | 8.125 × |
81250 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and fifty |
| Binary (base 2) | 10011110101100010 |
| Octal (base 8) | 236542 |
| Hexadecimal (base 16) | 13D62 |
| Base 3 | 11010110021 |
| As time | 81250 seconds = 22 h 34 min 10 s |
Is 81250 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81250 ÷ 2 = 40625) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | 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 (81250 ÷ 5 = 16250) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (81250 ÷ 10 = 8125) | 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 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81250 a prime number?
No. 81250 = 2 × × 13, so it is divisible by 2.
What are the factors of 81250?
1, 2, 5, 10, 13, 25, 26, 50, 65, 125, 130, 250, 325, 625, 650, 1250, 1625, 3125, 3250, 6250, 8125, 16250, 40625, 81250.
What is 81250 in binary?
10011110101100010 (hexadecimal 13D62, octal 236542).
What is the square root of 81250?
About 285.0439, exactly 25√130.
Is 81250 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 81250?
81250 is a happy number: repeatedly adding the squares of its digits reaches 1.