7
7 is a prime number. Like all primes greater than two, it is odd and has no factors apart from itself and one.
7 is a prime number. Like all primes (except two), it is an odd number.
Prime factorization of 7:
7
See below for interesting mathematical facts about the number 7 from the Numbermatics database.
Names of 7
 Cardinal: 7 can be written as Seven.
Scientific notation
 Scientific notation: 7 × 10^{0}
Factors of 7
 Number of distinct prime factors ω(n): 1
 Total number of prime factors Ω(n): 1
 Sum of prime factors: 7
Divisors of 7
 Number of divisors d(n): 2
 Complete list of divisors:
 Sum of all divisors σ(n): 8
 Sum of proper divisors (its aliquot sum) s(n): 1
 7 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 6
Bases of 7
 Binary: 111 _{2}
 Hexadecimal: 0x7
Squares and roots of 7
 7 squared (7^{2}) is 49
 7 cubed (7^{3}) is 343

The
square root of 7 is 2.6457513111 
The
cube root of 7 is 1.9129311827
Scales and comparisons
How big is 7?
To count from 1 to 7 would take you about three 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 randomlychosen 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 7 cubic inches would be around 0.2 feet tall.
Recreational maths with 7

7 is the same when its digits are reversed! That makes it a
palindromic prime number .  7 is a
Harshad number .  The number of decimal digits it has is: 1
 The sum of 7's digits is 7
 More coming soon!
The information we have on file for 7 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!
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