The number 9961
9961 is a composite number with 4 divisors. Its prime factorisation is 7 × 1423. Divisors (4): 1, 7, 1423, 9961.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 9961: a semiprime: 7 × 1423, the product of two primes.
- 2
9961 is composite. Its prime factorisation is
- 3
The divisors add up to 11392; without 9961 itself that is 1431, so 9961 is deficient (1431 is less than 9961). Euler's totient φ(9961) = 8532 numbers up to 9961 share no factor with it.
- 4
The digits of 9961 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 73 steps to reach 1.
LaTeX source of the formulas on this page
\[ 9961 = 7 \times 1423 \]
9961 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 11392 |
| Euler totient φ(n) | 8532 |
| Square | 99221521 |
| Cube | 988345570681 |
| Square root | 99.804810 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 73 |
| Scientific notation | 9.961 × |
9961 in other forms
| Form | Value |
|---|---|
| In words | nine thousand nine hundred and sixty-one |
| Binary (base 2) | 10011011101001 |
| Octal (base 8) | 23351 |
| Hexadecimal (base 16) | 26E9 |
| Base 3 | 111122221 |
| As time | 9961 seconds = 2 h 46 min 1 s |
Is 9961 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 (9961 ÷ 7 = 1423) | 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 1) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | 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 9961 a prime number?
No. 9961 = 7 × 1423, so it is divisible by 7.
What are the factors of 9961?
1, 7, 1423, 9961.
What is 9961 in binary?
10011011101001 (hexadecimal 26E9, octal 23351).
What is the square root of 9961?
About 99.8048.
Is 9961 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 9961?
9961 is a semiprime: 7 × 1423, the product of two primes.