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67 (sixty-seven) is the natural number following 66 and preceding 68. It is an odd number. In mathematics. 67 is: the 19th prime number (the next is 71).
Even and odd numbers: An integer is even if it is a multiple of 2, and is odd otherwise. 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 ...
n with an odd number of distinct prime factors (μ(n)=-1) 4 6 32 64 351 617 3438 6067 + + n even with an odd number of prime factors 1 2 9 21 100 180 1010 6067 + + n even with an odd number of distinct prime factors 3 4 21 49 268 482 2486 4452 + + n odd with an odd number of prime factors 3 4 23 43 251 437 2428 4315 + +
Except for 11, all palindromic primes have an odd number of digits, because the divisibility test for 11 tells us that every palindromic number with an even number of digits is a multiple of 11. It is not known if there are infinitely many palindromic primes in base 10.
The even numbers form an ideal in the ring of integers, [13] but the odd numbers do not—this is clear from the fact that the identity element for addition, zero, is an element of the even numbers only. An integer is even if it is congruent to 0 modulo this ideal, in other words if it is congruent to 0 modulo 2, and odd if it is congruent to 1 ...
An economical number has been defined as a frugal number, but also as a number that is either frugal or equidigital. gcd( m , n ) ( greatest common divisor of m and n ) is the product of all prime factors which are both in m and n (with the smallest multiplicity for m and n ).
Drinking coffee could extend your life up to two years, new research finds. Regular coffee consumption was found to be associated with increased health span (time spent living free from serious ...
The undulating number ABAB...ABA with n repetitions of AB followed by one A can be expressed as (AB × 10 2n+1 − BA)/99. For example, 989898989 = (98 × 10 9 − 89)/99; Undulating numbers can be generalized to other bases. If a number in base with even number of digits is undulating, in base it is a repdigit.