The number 21012
21012 is a palindrome: it reads 21012 backwards too. Its prime factorisation is × 3 × 17 × 103. Divisors (24): 1, 2, 3, 4, 6, 12, 17, 34, 51, 68, 102, 103, 204, 206, 309, 412 … 21012.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21012: a palindrome: it reads 21012 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 6.
- 2
21012 is composite. Its prime factorisation is
- 3
The divisors add up to 52416; without 21012 itself that is 31404, so 21012 is abundant (31404 is more than 21012). Euler's totient φ(21012) = 6528 numbers up to 21012 share no factor with it.
- 4
The digits of 21012 add up to 6, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21012 = 2^{2} \times 3 \times 17 \times 103 \]21012 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 52416 |
| Euler totient φ(n) | 6528 |
| Square | 441504144 |
| Cube | 9276885073728 |
| Square root | 144.955165 (= 2√5253) |
| Digit sum / digital root | 6 / 6 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1012 × |
21012 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and twelve |
| Binary (base 2) | 101001000010100 |
| Octal (base 8) | 51024 |
| Hexadecimal (base 16) | 5214 |
| Base 3 | 1001211020 |
| As time | 21012 seconds = 5 h 50 min 12 s |
Is 21012 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21012 ÷ 2 = 10506) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21012 ÷ 3 = 7004) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21012 ÷ 4 = 5253) | 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 | Yes (21012 ÷ 6 = 3502) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21012 ÷ 12 = 1751) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21012 a prime number?
No. 21012 = × 3 × 17 × 103, so it is divisible by 2.
What are the factors of 21012?
1, 2, 3, 4, 6, 12, 17, 34, 51, 68, 102, 103, 204, 206, 309, 412, 618, 1236, 1751, 3502, 5253, 7004, 10506, 21012.
What is 21012 in binary?
101001000010100 (hexadecimal 5214, octal 51024).
What is the square root of 21012?
About 144.9552, exactly 2√5253.
Is 21012 divisible by 3?
Yes. Its digits add up to 6, a multiple of 3.
What is special about the number 21012?
21012 is a palindrome: it reads 21012 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 6.