The number 81406
81406 is a triangular number: 1 + 2 + … + 403 = 81406. Its prime factorisation is 2 × 13 × 31 × 101. Divisors (16): 1, 2, 13, 26, 31, 62, 101, 202, 403, 806, 1313, 2626, 3131, 6262, 40703, 81406.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81406: a triangular number: 1 + 2 + … + 403 = 81406.
- 2
81406 is composite. Its prime factorisation is
- 3
The divisors add up to 137088; without 81406 itself that is 55682, so 81406 is deficient (55682 is less than 81406). Euler's totient φ(81406) = 36000 numbers up to 81406 share no factor with it.
- 4
The digits of 81406 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 257 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81406 = 2 \times 13 \times 31 \times 101 \]
81406 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 137088 |
| Euler totient φ(n) | 36000 |
| Square | 6626936836 |
| Cube | 539472420071416 |
| Square root | 285.317367 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 257 |
| Scientific notation | 8.1406 × |
81406 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred and six |
| Binary (base 2) | 10011110111111110 |
| Octal (base 8) | 236776 |
| Hexadecimal (base 16) | 13DFE |
| Base 3 | 11010200001 |
| As time | 81406 seconds = 22 h 36 min 46 s |
Is 81406 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81406 ÷ 2 = 40703) | 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 | No (remainder 1) | 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 3) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | 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 81406 a prime number?
No. 81406 = 2 × 13 × 31 × 101, so it is divisible by 2.
What are the factors of 81406?
1, 2, 13, 26, 31, 62, 101, 202, 403, 806, 1313, 2626, 3131, 6262, 40703, 81406.
What is 81406 in binary?
10011110111111110 (hexadecimal 13DFE, octal 236776).
What is the square root of 81406?
About 285.3174.
Is 81406 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 81406?
81406 is a triangular number: 1 + 2 + … + 403 = 81406.