The number 37821
37821 is a composite number with 8 divisors. Its prime factorisation is 3 × 7 × 1801. Divisors (8): 1, 3, 7, 21, 1801, 5403, 12607, 37821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 37821: a Harshad number: divisible by its digit sum 21.
- 2
37821 is composite. Its prime factorisation is
- 3
The divisors add up to 57664; without 37821 itself that is 19843, so 37821 is deficient (19843 is less than 37821). Euler's totient φ(37821) = 21600 numbers up to 37821 share no factor with it.
- 4
The digits of 37821 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 155 steps to reach 1.
LaTeX source of the formulas on this page
\[ 37821 = 3 \times 7 \times 1801 \]
37821 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 57664 |
| Euler totient φ(n) | 21600 |
| Square | 1430428041 |
| Cube | 54100218938661 |
| Square root | 194.476220 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 155 |
| Scientific notation | 3.7821 × |
37821 in other forms
| Form | Value |
|---|---|
| In words | thirty-seven thousand eight hundred and twenty-one |
| Binary (base 2) | 1001001110111101 |
| Octal (base 8) | 111675 |
| Hexadecimal (base 16) | 93BD |
| Base 3 | 1220212210 |
| As time | 37821 seconds = 10 h 30 min 21 s |
Is 37821 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (37821 ÷ 3 = 12607) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (37821 ÷ 7 = 5403) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 37821 a prime number?
No. 37821 = 3 × 7 × 1801, so it is divisible by 3.
What are the factors of 37821?
1, 3, 7, 21, 1801, 5403, 12607, 37821.
What is 37821 in binary?
1001001110111101 (hexadecimal 93BD, octal 111675).
What is the square root of 37821?
About 194.4762.
Is 37821 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 37821?
37821 is a Harshad number: divisible by its digit sum 21.