The number 81201
81201 is a composite number with 4 divisors. Its prime factorisation is 3 × 27067. Divisors (4): 1, 3, 27067, 81201.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81201: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 27067, the product of two primes.
- 2
81201 is composite. Its prime factorisation is
- 3
The divisors add up to 108272; without 81201 itself that is 27071, so 81201 is deficient (27071 is less than 81201). Euler's totient φ(81201) = 54132 numbers up to 81201 share no factor with it.
- 4
The digits of 81201 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 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81201 = 3 \times 27067 \]
81201 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 108272 |
| Euler totient φ(n) | 54132 |
| Square | 6593602401 |
| Cube | 535407108563601 |
| Square root | 284.957892 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1201 × |
81201 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and one |
| Binary (base 2) | 10011110100110001 |
| Octal (base 8) | 236461 |
| Hexadecimal (base 16) | 13D31 |
| Base 3 | 11010101110 |
| As time | 81201 seconds = 22 h 33 min 21 s |
Is 81201 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 (81201 ÷ 3 = 27067) | 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 | 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 1) | 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 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 81201 a prime number?
No. 81201 = 3 × 27067, so it is divisible by 3.
What are the factors of 81201?
1, 3, 27067, 81201.
What is 81201 in binary?
10011110100110001 (hexadecimal 13D31, octal 236461).
What is the square root of 81201?
About 284.9579.
Is 81201 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 81201?
81201 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 27067, the product of two primes.