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The sum 43 + 50 + 40 = 133 represents the one-hundredth composite number, [9] where the sum of all members in this aliquot sequence up to 70 is the fifty-ninth prime, 277 (this prime index value represents the seventeenth prime number and seventh super-prime, 59).
One way to classify composite numbers is by counting the number of prime factors. A composite number with two prime factors is a semiprime or 2-almost prime (the factors need not be distinct, hence squares of primes are included). A composite number with three distinct prime factors is a sphenic number. In some applications, it is necessary to ...
2.70 Wagstaff primes. ... A prime number (or prime) ... digits changed to any other value will always result in a composite number. 294001, 505447, 584141, 604171, ...
Therefore, every prime number other than 2 is an odd number, and is called an odd prime. [10] Similarly, when written in the usual decimal system, all prime numbers larger than 5 end in 1, 3, 7, or 9. The numbers that end with other digits are all composite: decimal numbers that end in 0, 2, 4, 6, or 8 are even, and decimal numbers that end in ...
Prime number: A positive integer with exactly two positive divisors: itself and 1. The primes form an infinite sequence 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, ... Composite number: A positive integer that can be factored into a product of smaller positive integers. Every integer greater than one is either prime or composite.
In number theory, a weird number is a natural number that is abundant but not semiperfect. [ 1 ] [ 2 ] In other words, the sum of the proper divisors ( divisors including 1 but not itself) of the number is greater than the number, but no subset of those divisors sums to the number itself.
A list of articles about numbers (not about numerals). Topics include powers of ten, notable integers, prime and cardinal numbers, and the myriad system.
Ω(n), the prime omega function, is the number of prime factors of n counted with multiplicity (so it is the sum of all prime factor multiplicities). A prime number has Ω(n) = 1. The first: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37 (sequence A000040 in the OEIS). There are many special types of prime numbers. A composite number has Ω(n) > 1.