The number 16921
16921 is the 1951st prime number. Its only divisors are 1 and 16921.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 16921: the 1951st prime number.
- 2
16921 is prime, so its only factors are 1 and 16921. It is the 1951st prime; the next prime is 16927 and the one before is 16903.
- 3
The divisors add up to 16922; without 16921 itself that is 1, so 16921 is deficient (1 is less than 16921). Euler's totient φ(16921) = 16920 numbers up to 16921 share no factor with it.
- 4
The digits of 16921 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 84 steps to reach 1.
16921 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 16922 |
| Euler totient φ(n) | 16920 |
| Square | 286320241 |
| Cube | 4844824797961 |
| Square root | 130.080744 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 84 |
| Scientific notation | 1.6921 × |
16921 in other forms
| Form | Value |
|---|---|
| In words | sixteen thousand nine hundred and twenty-one |
| Binary (base 2) | 100001000011001 |
| Octal (base 8) | 41031 |
| Hexadecimal (base 16) | 4219 |
| Base 3 | 212012201 |
| As time | 16921 seconds = 4 h 42 min 1 s |
Is 16921 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 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 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 3) | 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 16921 a prime number?
Yes. 16921 is divisible only by 1 and itself.
What are the factors of 16921?
1, 16921.
What is 16921 in binary?
100001000011001 (hexadecimal 4219, octal 41031).
What is the square root of 16921?
About 130.0807.
Is 16921 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 16921?
16921 is the 1951st prime number.