The number 21023
21023 is the 2366th prime number. Its only divisors are 1 and 21023.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21023: the 2366th prime number.
- 2
21023 is prime, so its only factors are 1 and 21023. It is the 2366th prime; the next prime is 21031 and the one before is 21019.
- 3
The divisors add up to 21024; without 21023 itself that is 1, so 21023 is deficient (1 is less than 21023). Euler's totient φ(21023) = 21022 numbers up to 21023 share no factor with it.
- 4
The digits of 21023 add up to 8, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
21023 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21024 |
| Euler totient φ(n) | 21022 |
| Square | 441966529 |
| Cube | 9291462339167 |
| Square root | 144.993103 |
| Digit sum / digital root | 8 / 8 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1023 × |
21023 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and twenty-three |
| Binary (base 2) | 101001000011111 |
| Octal (base 8) | 51037 |
| Hexadecimal (base 16) | 521F |
| Base 3 | 1001211122 |
| As time | 21023 seconds = 5 h 50 min 23 s |
Is 21023 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 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21023 a prime number?
Yes. 21023 is divisible only by 1 and itself.
What are the factors of 21023?
1, 21023.
What is 21023 in binary?
101001000011111 (hexadecimal 521F, octal 51037).
What is the square root of 21023?
About 144.9931.
Is 21023 divisible by 3?
No. Its digits add up to 8, which is not a multiple of 3.
What is special about the number 21023?
21023 is the 2366th prime number.