The number 81372
81372 is a composite number with 12 divisors. Its prime factorisation is × 3 × 6781. Divisors (12): 1, 2, 3, 4, 6, 12, 6781, 13562, 20343, 27124, 40686, 81372.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
81372 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81372 is composite. Its prime factorisation is
- 3
The divisors add up to 189896; without 81372 itself that is 108524, so 81372 is abundant (108524 is more than 81372). Euler's totient φ(81372) = 27120 numbers up to 81372 share no factor with it.
- 4
The digits of 81372 add up to 21, 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
\[ 81372 = 2^{2} \times 3 \times 6781 \]81372 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 189896 |
| Euler totient φ(n) | 27120 |
| Square | 6621402384 |
| Cube | 538796754790848 |
| Square root | 285.257778 (= 2√20343) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1372 × |
81372 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand three hundred and seventy-two |
| Binary (base 2) | 10011110111011100 |
| Octal (base 8) | 236734 |
| Hexadecimal (base 16) | 13DDC |
| Base 3 | 11010121210 |
| As time | 81372 seconds = 22 h 36 min 12 s |
Is 81372 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81372 ÷ 2 = 40686) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81372 ÷ 3 = 27124) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (81372 ÷ 4 = 20343) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (81372 ÷ 6 = 13562) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 4) | 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 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (81372 ÷ 12 = 6781) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81372 a prime number?
No. 81372 = × 3 × 6781, so it is divisible by 2.
What are the factors of 81372?
1, 2, 3, 4, 6, 12, 6781, 13562, 20343, 27124, 40686, 81372.
What is 81372 in binary?
10011110111011100 (hexadecimal 13DDC, octal 236734).
What is the square root of 81372?
About 285.2578, exactly 2√20343.
Is 81372 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 81372?
It is a composite number with 12 divisors.