The number 21400
21400 is a composite number with 24 divisors. Its prime factorisation is × × 107. Divisors (24): 1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 107, 200, 214, 428, 535 … 21400.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21400 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21400 is composite. Its prime factorisation is
- 3
The divisors add up to 50220; without 21400 itself that is 28820, so 21400 is abundant (28820 is more than 21400). Euler's totient φ(21400) = 8480 numbers up to 21400 share no factor with it.
- 4
The digits of 21400 add up to 7, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21400 = 2^{3} \times 5^{2} \times 107 \]21400 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 50220 |
| Euler totient φ(n) | 8480 |
| Square | 457960000 |
| Cube | 9800344000000 |
| Square root | 146.287388 (= 10√214) |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.14 × |
21400 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred |
| Binary (base 2) | 101001110011000 |
| Octal (base 8) | 51630 |
| Hexadecimal (base 16) | 5398 |
| Base 3 | 1002100121 |
| As time | 21400 seconds = 5 h 56 min 40 s |
Is 21400 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21400 ÷ 2 = 10700) | 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 | Yes (21400 ÷ 4 = 5350) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21400 ÷ 5 = 4280) | 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 | No (remainder 1) | 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 | Yes (21400 ÷ 8 = 2675) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21400 ÷ 10 = 2140) | 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 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21400 a prime number?
No. 21400 = × × 107, so it is divisible by 2.
What are the factors of 21400?
1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 107, 200, 214, 428, 535, 856, 1070, 2140, 2675, 4280, 5350, 10700, 21400.
What is 21400 in binary?
101001110011000 (hexadecimal 5398, octal 51630).
What is the square root of 21400?
About 146.2874, exactly 10√214.
Is 21400 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 21400?
It is a composite number with 24 divisors.