The number 90021
90021 is a composite number with 8 divisors. Its prime factorisation is 3 × 37 × 811. Divisors (8): 1, 3, 37, 111, 811, 2433, 30007, 90021.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 90021: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
90021 is composite. Its prime factorisation is
- 3
The divisors add up to 123424; without 90021 itself that is 33403, so 90021 is deficient (33403 is less than 90021). Euler's totient φ(90021) = 58320 numbers up to 90021 share no factor with it.
- 4
The digits of 90021 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
\[ 90021 = 3 \times 37 \times 811 \]
90021 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 123424 |
| Euler totient φ(n) | 58320 |
| Square | 8103780441 |
| Cube | 729510419079261 |
| Square root | 300.034998 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 89 |
| Scientific notation | 9.0021 × |
90021 in other forms
| Form | Value |
|---|---|
| In words | ninety thousand and twenty-one |
| Binary (base 2) | 10101111110100101 |
| Octal (base 8) | 257645 |
| Hexadecimal (base 16) | 15FA5 |
| Base 3 | 11120111010 |
| As time | 90021 seconds = 25 h 0 min 21 s |
Is 90021 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 (90021 ÷ 3 = 30007) | 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 5) | 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 8) | 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 90021 a prime number?
No. 90021 = 3 × 37 × 811, so it is divisible by 3.
What are the factors of 90021?
1, 3, 37, 111, 811, 2433, 30007, 90021.
What is 90021 in binary?
10101111110100101 (hexadecimal 15FA5, octal 257645).
What is the square root of 90021?
About 300.0350.
Is 90021 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 90021?
90021 is a happy number: repeatedly adding the squares of its digits reaches 1.