The number 21070
21070 is a composite number with 24 divisors. Its prime factorisation is 2 × 5 × × 43. Divisors (24): 1, 2, 5, 7, 10, 14, 35, 43, 49, 70, 86, 98, 215, 245, 301, 430 … 21070.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21070: a Harshad number: divisible by its digit sum 10.
- 2
21070 is composite. Its prime factorisation is
- 3
The divisors add up to 45144; without 21070 itself that is 24074, so 21070 is abundant (24074 is more than 21070). Euler's totient φ(21070) = 7056 numbers up to 21070 share no factor with it.
- 4
The digits of 21070 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 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21070 = 2 \times 5 \times 7^{2} \times 43 \]21070 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 45144 |
| Euler totient φ(n) | 7056 |
| Square | 443944900 |
| Cube | 9353919043000 |
| Square root | 145.155089 (= 7√430) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.107 × |
21070 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and seventy |
| Binary (base 2) | 101001001001110 |
| Octal (base 8) | 51116 |
| Hexadecimal (base 16) | 524E |
| Base 3 | 1001220101 |
| As time | 21070 seconds = 5 h 51 min 10 s |
Is 21070 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21070 ÷ 2 = 10535) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21070 ÷ 5 = 4214) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21070 ÷ 7 = 3010) | 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 6) | 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 | Yes (21070 ÷ 10 = 2107) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21070 a prime number?
No. 21070 = 2 × 5 × × 43, so it is divisible by 2.
What are the factors of 21070?
1, 2, 5, 7, 10, 14, 35, 43, 49, 70, 86, 98, 215, 245, 301, 430, 490, 602, 1505, 2107, 3010, 4214, 10535, 21070.
What is 21070 in binary?
101001001001110 (hexadecimal 524E, octal 51116).
What is the square root of 21070?
About 145.1551, exactly 7√430.
Is 21070 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21070?
21070 is a Harshad number: divisible by its digit sum 10.