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The basic rule for divisibility by 4 is that if the number formed by the last two digits in a number is divisible by 4, the original number is divisible by 4; [2] [3] this is because 100 is divisible by 4 and so adding hundreds, thousands, etc. is simply adding another number that is divisible by 4. If any number ends in a two digit number that ...
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
For example, there are six divisors of 4; they are 1, 2, 4, −1, −2, and −4, but only the positive ones (1, 2, and 4) would usually be mentioned. 1 and −1 divide (are divisors of) every integer. Every integer (and its negation) is a divisor of itself. Integers divisible by 2 are called even, and integers not divisible by 2 are called odd.
Each natural number divisible by 4 is a difference of squares of two natural numbers, i.e. =. A four-sided plane figure is a quadrilateral or quadrangle, sometimes also called a tetragon. It can be further classified as a rectangle or oblong, kite, rhombus, and square.
65 = 1 5 + 2 4 + 3 3 + 4 2 + 5 1. [9] 65 is the length of the hypotenuse of 4 different Pythagorean triangles, the lowest number to have more than 2: 65 2 = 16 2 + 63 2 = 33 2 + 56 2 = 39 2 + 52 2 = 25 2 + 60 2. [10] The first two are "primitive", and 65 is the lowest number to be the largest side of more than one such triple. [11] 65 is the ...
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. [ 9 ] [ 10 ] Also, a pair of co-prime amicable numbers cannot be generated by Thabit's formula (above), nor by any similar formula.
It is the smallest number divisible by the numbers 1 to 6: there is no smaller number divisible by the numbers 1 to 5 since any number divisible by 2 and 3 must also be divisible by 6. It is the smallest number with exactly 12 divisors. Having 12 as one of those divisors, 60 is also a refactorable number.
65536 is the natural number following 65535 and preceding 65537.. 65536 is a power of two: (2 to the 16th power).. 65536 is the smallest number with exactly 17 divisors (but there are smaller numbers with more than 17 divisors; e.g., 180 has 18 divisors) (sequence A005179 in the OEIS).