The number 81400
81400 is a composite number with 48 divisors. Its prime factorisation is × × 11 × 37. Divisors (48): 1, 2, 4, 5, 8, 10, 11, 20, 22, 25, 37, 40, 44, 50, 55, 74 … 81400.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
81400 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81400 is composite. Its prime factorisation is
- 3
The divisors add up to 212040; without 81400 itself that is 130640, so 81400 is abundant (130640 is more than 81400). Euler's totient φ(81400) = 28800 numbers up to 81400 share no factor with it.
- 4
The digits of 81400 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 182 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81400 = 2^{3} \times 5^{2} \times 11 \times 37 \]81400 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 212040 |
| Euler totient φ(n) | 28800 |
| Square | 6625960000 |
| Cube | 539353144000000 |
| Square root | 285.306852 (= 10√814) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 182 |
| Scientific notation | 8.14 × |
81400 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred |
| Binary (base 2) | 10011110111111000 |
| Octal (base 8) | 236770 |
| Hexadecimal (base 16) | 13DF8 |
| Base 3 | 11010122211 |
| As time | 81400 seconds = 22 h 36 min 40 s |
Is 81400 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81400 ÷ 2 = 40700) | 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 | Yes (81400 ÷ 4 = 20350) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (81400 ÷ 5 = 16280) | 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 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 | Yes (81400 ÷ 8 = 10175) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (81400 ÷ 10 = 8140) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (81400 ÷ 11 = 7400) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81400 a prime number?
No. 81400 = × × 11 × 37, so it is divisible by 2.
What are the factors of 81400?
1, 2, 4, 5, 8, 10, 11, 20, 22, 25, 37, 40, 44, 50, 55, 74, 88, 100, 110, 148, 185, 200, 220, 275, 296, 370, 407, 440, 550, 740, 814, 925, 1100, 1480, 1628, 1850, 2035, 2200, 3256, 3700, 4070, 7400, 8140, 10175, 16280, 20350, 40700, 81400.
What is 81400 in binary?
10011110111111000 (hexadecimal 13DF8, octal 236770).
What is the square root of 81400?
About 285.3069, exactly 10√814.
Is 81400 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 81400?
It is a composite number with 48 divisors.