The number 21601
21601 is a twin prime (21599 and 21601 are both prime) and the 2426th prime number. Its only divisors are 1 and 21601.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21601: a twin prime (21599 and 21601 are both prime); the 2426th prime number.
- 2
21601 is prime, so its only factors are 1 and 21601. It is the 2426th prime; the next prime is 21611 and the one before is 21599.
- 3
The divisors add up to 21602; without 21601 itself that is 1, so 21601 is deficient (1 is less than 21601). Euler's totient φ(21601) = 21600 numbers up to 21601 share no factor with it.
- 4
The digits of 21601 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 69 steps to reach 1.
21601 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21602 |
| Euler totient φ(n) | 21600 |
| Square | 466603201 |
| Cube | 10079095744801 |
| Square root | 146.972787 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.1601 × |
21601 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and one |
| Binary (base 2) | 101010001100001 |
| Octal (base 8) | 52141 |
| Hexadecimal (base 16) | 5461 |
| Base 3 | 1002122001 |
| As time | 21601 seconds = 6 h 0 min 1 s |
Is 21601 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 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 1) | 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 8) | 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 21601 a prime number?
Yes. 21601 is divisible only by 1 and itself.
What are the factors of 21601?
1, 21601.
What is 21601 in binary?
101010001100001 (hexadecimal 5461, octal 52141).
What is the square root of 21601?
About 146.9728.
Is 21601 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21601?
21601 is a twin prime (21599 and 21601 are both prime); the 2426th prime number.