15 is an odd composite number. It is composed of two distinct prime numbers multiplied together. It has a total of four divisors.
Prime factorization of 15:
3 × 5
3 × 5
See below for interesting mathematical facts about the number 15 from the Numbermatics database.
Names of 15
- Cardinal: 15 can be written as Fifteen.
- Scientific notation: 1.5 × 101
Factors of 15
- Number of distinct prime factors ω(n): 2
- Total number of prime factors Ω(n): 2
- Sum of prime factors: 8
Divisors of 15
- Number of divisors d(n): 4
- Complete list of divisors:
- Sum of all divisors σ(n): 24
- Sum of proper divisors (its aliquot sum) s(n): 9
- 15 is a deficient number, because the sum of its proper divisors (9) is less than itself. Its deficiency is 6
Bases of 15
- Binary: 1111 2
- Hexadecimal: 0xf
Squares and roots of 15
- 15 squared (152) is 225
- 15 cubed (153) is 3375
square rootof 15 is 3.8729833463
cube rootof 15 is 2.4662120743
Scales and comparisonsHow big is 15?
To count from 1 to 15 would take you about seven seconds.
This is a very rough estimate, based on a speaking rate of half a second every third order of magnitude. If you speak quickly, you could probably say any randomly-chosen number between one and a thousand in around half a second. Very big numbers obviously take longer to say, so we add half a second for every extra x1000.
Note: we do not count involuntary pauses, bathroom breaks or the necessity of sleep in our calculation!
- A cube with a volume of 15 cubic inches would be around 0.2 feet tall.
Recreational maths with 15
- 15 backwards is 51
- The number of decimal digits it has is: 2
- The sum of 15's digits is 6
- More coming soon!
The information we have on file for 15 includes mathematical data and numerical statistics calculated using standard algorithms and methods. We are adding more all the time. If there are any features you would like to see, please contact us. Information provided for educational use, intellectual curiosity and fun!