The number 21202
21202 is a composite number with 4 divisors. Its prime factorisation is 2 × 10601. Divisors (4): 1, 2, 10601, 21202.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21202: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10601, the product of two primes.
- 2
21202 is composite. Its prime factorisation is
- 3
The divisors add up to 31806; without 21202 itself that is 10604, so 21202 is deficient (10604 is less than 21202). Euler's totient φ(21202) = 10600 numbers up to 21202 share no factor with it.
- 4
The digits of 21202 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 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21202 = 2 \times 10601 \]
21202 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 31806 |
| Euler totient φ(n) | 10600 |
| Square | 449524804 |
| Cube | 9530824894408 |
| Square root | 145.609066 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1202 × |
21202 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and two |
| Binary (base 2) | 101001011010010 |
| Octal (base 8) | 51322 |
| Hexadecimal (base 16) | 52D2 |
| Base 3 | 1002002021 |
| As time | 21202 seconds = 5 h 53 min 22 s |
Is 21202 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21202 ÷ 2 = 10601) | 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 | No (remainder 2) | 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 6) | 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 7) | 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 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 21202 a prime number?
No. 21202 = 2 × 10601, so it is divisible by 2.
What are the factors of 21202?
1, 2, 10601, 21202.
What is 21202 in binary?
101001011010010 (hexadecimal 52D2, octal 51322).
What is the square root of 21202?
About 145.6091.
Is 21202 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 21202?
21202 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10601, the product of two primes.