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m is a divisor of n (also called m divides n, or n is divisible by m) if all prime factors of m have at least the same multiplicity in n. The divisors of n are all products of some or all prime factors of n (including the empty product 1 of no prime factors). The number of divisors can be computed by increasing all multiplicities by 1 and then ...
Two numbers with the same "abundancy" form a friendly pair; ... 51: 72: 24/17 52: 98: 49/26 ... at least one of the prime factors must be congruent to 1 modulo 3 and ...
a Størmer number, since the greatest prime factor of 51 2 + 1 = 2602 is 1301, which is substantially more than 51 twice. [6] There are 51 different cyclic Gilbreath permutations on 10 elements, [7] and therefore there are 51 different real periodic points of order 10 on the Mandelbrot set. [8]
The semiprimes are the case = of the -almost primes, numbers with exactly prime factors. However some sources use "semiprime" to refer to a larger set of numbers, the numbers with at most two prime factors (including unit (1), primes, and semiprimes). [3]
If one of the factors is composite, it can in turn be written as a product of smaller factors, for example 60 = 3 · 20 = 3 · (5 · 4). Continuing this process until every factor is prime is called prime factorization; the result is always unique up to the order of the factors by the prime factorization theorem.
However, amicable numbers where the two members have different smallest prime factors do exist: there are seven such pairs known. [8] Also, every known pair shares at least one common prime factor. It is not known whether a pair of coprime amicable numbers exists, though if any does, the product of the two must be greater than 10 65.
Compute the remainder of each digit pair (from right to left) when divided by 7. ... 408 = 8 × 51. ... the factors of 10 1 include 2, 5, and 10. Therefore ...
d() is the number of positive divisors of n, including 1 and n itself; σ() is the sum of the positive divisors of n, including 1 and n itselfs() is the sum of the proper divisors of n, including 1 but not n itself; that is, s(n) = σ(n) − n