The number 65421
65421 is a composite number with 8 divisors. Its prime factorisation is × 2423. Divisors (8): 1, 3, 9, 27, 2423, 7269, 21807, 65421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 65421: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
65421 is composite. Its prime factorisation is
- 3
The divisors add up to 96960; without 65421 itself that is 31539, so 65421 is deficient (31539 is less than 65421). Euler's totient φ(65421) = 43596 numbers up to 65421 share no factor with it.
- 4
The digits of 65421 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 55 steps to reach 1.
LaTeX source of the formulas on this page
\[ 65421 = 3^{3} \times 2423 \]65421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 96960 |
| Euler totient φ(n) | 43596 |
| Square | 4279907241 |
| Cube | 279995811613461 |
| Square root | 255.775292 (= 3√7269) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 55 |
| Scientific notation | 6.5421 × |
65421 in other forms
| Form | Value |
|---|---|
| In words | sixty-five thousand four hundred and twenty-one |
| Binary (base 2) | 1111111110001101 |
| Octal (base 8) | 177615 |
| Hexadecimal (base 16) | FF8D |
| Base 3 | 10022202000 |
| As time | 65421 seconds = 18 h 10 min 21 s |
Is 65421 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 (65421 ÷ 3 = 21807) | 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 6) | 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 | Yes (65421 ÷ 9 = 7269) | 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 4) | 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 65421 a prime number?
No. 65421 = × 2423, so it is divisible by 3.
What are the factors of 65421?
1, 3, 9, 27, 2423, 7269, 21807, 65421.
What is 65421 in binary?
1111111110001101 (hexadecimal FF8D, octal 177615).
What is the square root of 65421?
About 255.7753, exactly 3√7269.
Is 65421 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 65421?
65421 is a happy number: repeatedly adding the squares of its digits reaches 1.