The number 81501
81501 is a composite number with 8 divisors. Its prime factorisation is 3 × 7 × 3881. Divisors (8): 1, 3, 7, 21, 3881, 11643, 27167, 81501.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81501: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81501 is composite. Its prime factorisation is
- 3
The divisors add up to 124224; without 81501 itself that is 42723, so 81501 is deficient (42723 is less than 81501). Euler's totient φ(81501) = 46560 numbers up to 81501 share no factor with it.
- 4
The digits of 81501 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 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81501 = 3 \times 7 \times 3881 \]
81501 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 124224 |
| Euler totient φ(n) | 46560 |
| Square | 6642413001 |
| Cube | 541363301994501 |
| Square root | 285.483800 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.1501 × |
81501 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand five hundred and one |
| Binary (base 2) | 10011111001011101 |
| Octal (base 8) | 237135 |
| Hexadecimal (base 16) | 13E5D |
| Base 3 | 11010210120 |
| As time | 81501 seconds = 22 h 38 min 21 s |
Is 81501 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81501 ÷ 3 = 27167) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (81501 ÷ 7 = 11643) | 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 5) | 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 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81501 a prime number?
No. 81501 = 3 × 7 × 3881, so it is divisible by 3.
What are the factors of 81501?
1, 3, 7, 21, 3881, 11643, 27167, 81501.
What is 81501 in binary?
10011111001011101 (hexadecimal 13E5D, octal 237135).
What is the square root of 81501?
About 285.4838.
Is 81501 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 81501?
81501 is a happy number: repeatedly adding the squares of its digits reaches 1.