Number of the day: 6939

Properties of the number 6939:

6939 = 3³ × 257 is the 6048^th composite number and is not squarefree.
6939 has 2 distinct prime factors, 8 divisors, 7 antidivisors and 4608 totatives.
6939 = 3470² - 3469² = 1158² - 1155² = 390² - 381² = 142² - 115² is the difference of 2 nonnegative squares in 4 ways.
6939 is the sum of 2 positive triangular numbers.
6939 is the difference of 2 positive pentagonal numbers in 1 way.
6939 = 13² + 23² + 79² is the sum of 3 positive squares.
6939² = 864² + 6885² is the sum of 2 positive squares in 1 way.
6939² is the sum of 3 positive squares.
6939 is a divisor of 1783⁴ - 1.
6939 = '6' + '939' is the concatenation of 2 semiprime numbers.
6939 is palindromic in (at least) the following bases: 2, 29, and -51.
6939 in base 16 = 1b1b and consists of only the digits '1' and 'b'.
6939 in base 21 = ff9 and consists of only the digits '9' and 'f'.
6939 in base 28 = 8nn and consists of only the digits '8' and 'n'.
6939 in base 29 = 878 and consists of only the digits '7' and '8'.

The number 6939 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A033681: a(1) = 3; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.
A048710: Family 1 "Rule 90 x Rule 150 Array" read by antidiagonals.
A068221: An auxiliary bit-mask sequence for computing A066425. (The "clean", symmetric one).
A074338: a(1) = 2; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.
A107264: Expansion of (1-3x-sqrt((1-3x)^2-4*3*x^2))/(2*3*x^2).
A107267: A square array of Motzkin related transforms, read by antidiagonals.
A111471: a(1) = 1; for n>1, a(n) = least k such that concatenation of n copies of k with all previous concatenations gives a prime.
A195278: T(n,k)=Number of lower triangles of an n X n integer array with each element differing from all of its vertical and horizontal neighbors by k or less and triangles differing by a constant counted only once
A223556: T(n,k)=Petersen graph (3,1) coloring a rectangular array: number of nXk 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0
A249184: A249183 seen as binary numbers.