The number 15121
15121 is the 1766th prime number. Its only divisors are 1 and 15121.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15121: the 1766th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
15121 is prime, so its only factors are 1 and 15121. It is the 1766th prime; the next prime is 15131 and the one before is 15107.
- 3
The divisors add up to 15122; without 15121 itself that is 1, so 15121 is deficient (1 is less than 15121). Euler's totient φ(15121) = 15120 numbers up to 15121 share no factor with it.
- 4
The digits of 15121 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 84 steps to reach 1.
15121 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 15122 |
| Euler totient φ(n) | 15120 |
| Square | 228644641 |
| Cube | 3457335616561 |
| Square root | 122.967475 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 84 |
| Scientific notation | 1.5121 × |
15121 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand one hundred and twenty-one |
| Binary (base 2) | 11101100010001 |
| Octal (base 8) | 35421 |
| Hexadecimal (base 16) | 3B11 |
| Base 3 | 202202001 |
| As time | 15121 seconds = 4 h 12 min 1 s |
Is 15121 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 | 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 | No (remainder 1) | 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 7) | 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 15121 a prime number?
Yes. 15121 is divisible only by 1 and itself.
What are the factors of 15121?
1, 15121.
What is 15121 in binary?
11101100010001 (hexadecimal 3B11, octal 35421).
What is the square root of 15121?
About 122.9675.
Is 15121 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 15121?
15121 is the 1766th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.