The number 21061
21061 is a twin prime (21059 and 21061 are both prime) and the 2369th prime number. Its only divisors are 1 and 21061.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21061: a twin prime (21059 and 21061 are both prime); the 2369th prime number.
- 2
21061 is prime, so its only factors are 1 and 21061. It is the 2369th prime; the next prime is 21067 and the one before is 21059.
- 3
The divisors add up to 21062; without 21061 itself that is 1, so 21061 is deficient (1 is less than 21061). Euler's totient φ(21061) = 21060 numbers up to 21061 share no factor with it.
- 4
The digits of 21061 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 43 steps to reach 1.
21061 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21062 |
| Euler totient φ(n) | 21060 |
| Square | 443565721 |
| Cube | 9341937649981 |
| Square root | 145.124085 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.1061 × |
21061 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and sixty-one |
| Binary (base 2) | 101001001000101 |
| Octal (base 8) | 51105 |
| Hexadecimal (base 16) | 5245 |
| Base 3 | 1001220001 |
| As time | 21061 seconds = 5 h 51 min 1 s |
Is 21061 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 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 1) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21061 a prime number?
Yes. 21061 is divisible only by 1 and itself.
What are the factors of 21061?
1, 21061.
What is 21061 in binary?
101001001000101 (hexadecimal 5245, octal 51105).
What is the square root of 21061?
About 145.1241.
Is 21061 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21061?
21061 is a twin prime (21059 and 21061 are both prime); the 2369th prime number.