The number 7021
7021 is a triangular number: 1 + 2 + … + 118 = 7021. Its prime factorisation is 7 × 17 × 59. Divisors (8): 1, 7, 17, 59, 119, 413, 1003, 7021.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7021: a triangular number: 1 + 2 + … + 118 = 7021.
- 2
7021 is composite. Its prime factorisation is
- 3
The divisors add up to 8640; without 7021 itself that is 1619, so 7021 is deficient (1619 is less than 7021). Euler's totient φ(7021) = 5568 numbers up to 7021 share no factor with it.
- 4
The digits of 7021 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 44 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7021 = 7 \times 17 \times 59 \]
7021 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 8640 |
| Euler totient φ(n) | 5568 |
| Square | 49294441 |
| Cube | 346096270261 |
| Square root | 83.791408 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 44 |
| Scientific notation | 7.021 × |
7021 in other forms
| Form | Value |
|---|---|
| In words | seven thousand and twenty-one |
| Binary (base 2) | 1101101101101 |
| Octal (base 8) | 15555 |
| Hexadecimal (base 16) | 1B6D |
| Base 3 | 100122001 |
| As time | 7021 seconds = 1 h 57 min 1 s |
Is 7021 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 | No (remainder 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (7021 ÷ 7 = 1003) | 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 1) | 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 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 7021 a prime number?
No. 7021 = 7 × 17 × 59, so it is divisible by 7.
What are the factors of 7021?
1, 7, 17, 59, 119, 413, 1003, 7021.
What is 7021 in binary?
1101101101101 (hexadecimal 1B6D, octal 15555).
What is the square root of 7021?
About 83.7914.
Is 7021 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 7021?
7021 is a triangular number: 1 + 2 + … + 118 = 7021.