The number 21770
21770 is a composite number with 16 divisors. Its prime factorisation is 2 × 5 × 7 × 311. Divisors (16): 1, 2, 5, 7, 10, 14, 35, 70, 311, 622, 1555, 2177, 3110, 4354, 10885, 21770.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21770: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21770 is composite. Its prime factorisation is
- 3
The divisors add up to 44928; without 21770 itself that is 23158, so 21770 is abundant (23158 is more than 21770). Euler's totient φ(21770) = 7440 numbers up to 21770 share no factor with it.
- 4
The digits of 21770 add up to 17, 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.
LaTeX source of the formulas on this page
\[ 21770 = 2 \times 5 \times 7 \times 311 \]
21770 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 44928 |
| Euler totient φ(n) | 7440 |
| Square | 473932900 |
| Cube | 10317519233000 |
| Square root | 147.546603 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.177 × |
21770 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and seventy |
| Binary (base 2) | 101010100001010 |
| Octal (base 8) | 52412 |
| Hexadecimal (base 16) | 550A |
| Base 3 | 1002212022 |
| As time | 21770 seconds = 6 h 2 min 50 s |
Is 21770 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21770 ÷ 2 = 10885) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21770 ÷ 5 = 4354) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21770 ÷ 7 = 3110) | 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 2) | 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 | Yes (21770 ÷ 10 = 2177) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21770 a prime number?
No. 21770 = 2 × 5 × 7 × 311, so it is divisible by 2.
What are the factors of 21770?
1, 2, 5, 7, 10, 14, 35, 70, 311, 622, 1555, 2177, 3110, 4354, 10885, 21770.
What is 21770 in binary?
101010100001010 (hexadecimal 550A, octal 52412).
What is the square root of 21770?
About 147.5466.
Is 21770 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21770?
21770 is a happy number: repeatedly adding the squares of its digits reaches 1.