The number 21977
21977 is the 2462nd prime number. Its only divisors are 1 and 21977.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21977: the 2462nd prime number.
- 2
21977 is prime, so its only factors are 1 and 21977. It is the 2462nd prime; the next prime is 21991 and the one before is 21961.
- 3
The divisors add up to 21978; without 21977 itself that is 1, so 21977 is deficient (1 is less than 21977). Euler's totient φ(21977) = 21976 numbers up to 21977 share no factor with it.
- 4
The digits of 21977 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
21977 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21978 |
| Euler totient φ(n) | 21976 |
| Square | 482988529 |
| Cube | 10614638901833 |
| Square root | 148.246416 |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.1977 × |
21977 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and seventy-seven |
| Binary (base 2) | 101010111011001 |
| Octal (base 8) | 52731 |
| Hexadecimal (base 16) | 55D9 |
| Base 3 | 1010010222 |
| As time | 21977 seconds = 6 h 6 min 17 s |
Is 21977 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 4) | 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 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21977 a prime number?
Yes. 21977 is divisible only by 1 and itself.
What are the factors of 21977?
1, 21977.
What is 21977 in binary?
101010111011001 (hexadecimal 55D9, octal 52731).
What is the square root of 21977?
About 148.2464.
Is 21977 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 21977?
21977 is the 2462nd prime number.