Number of the day: 21478

Properties of the number 21478:

21478 = 2 × 10739 is semiprime and squarefree.
21478 has 2 distinct prime factors, 4 divisors, 25 antidivisors and 10738 totatives.
21478 has a semiprime digit sum 22 in base 10.
21478 has sum of divisors equal to 32220 which is an oblong number.
21478 is the sum of 2 positive triangular numbers.
21478 is the difference of 2 positive pentagonal numbers in 2 ways.
21478 = 21² + 34² + 141² is the sum of 3 positive squares.
21478² is the sum of 3 positive squares.
21478 is a proper divisor of 853⁵⁹ - 1.
21478 = '21' + '478' is the concatenation of 2 semiprime numbers.
21478 is an emirpimes in (at least) the following bases: 2, 8, 11, 13, 14, 16, 17, 18, 20, 21, 24, 26, 28, 30, 31, 35, 37, 39, 40, 41, 43, 46, 50, 51, 53, 55, 59, 63, 64, 69, 74, 76, 82, 84, 89, 92, and 95.
21478 is palindromic in (at least) the following bases: 91, and -61.

The number 21478 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A024588: a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers).
A092310: Sum of largest parts (counted with multiplicity) of all partitions of n into odd parts.
A116705: Number of permutations of length n which avoid the patterns 1234, 4312.
A187378: Number of 4-step S, NW and NE-moving king's tours on an n X n board summed over all starting positions
A229063: Volume of the Johnson square pyramid (rounded down) with all the edge lengths equal to n.
A304384: a(n) = 168*2^n - 26 (n>=1).