Number of the day: 8815

Properties of the number 8815:

8815 = 5 × 41 × 43 is a sphenic number and squarefree.
8815 has 3 distinct prime factors, 8 divisors, 17 antidivisors and 6720 totatives.
8815 has a semiprime digit sum 22 in base 10.
8815 = 4408² - 4407² = 884² - 879² = 128² - 87² = 124² - 81² is the difference of 2 nonnegative squares in 4 ways.
8815 is the sum of 2 positive triangular numbers.
8815 is the difference of 2 positive pentagonal numbers in 3 ways.
8815 is not the sum of 3 positive squares.
8815² = 3612² + 8041² = 1935² + 8600² = 5719² + 6708² = 5289² + 7052² is the sum of 2 positive squares in 4 ways.
8815² is the sum of 3 positive squares.
8815 is a divisor of 1721² - 1.
8815 = '881' + '5' is the concatenation of 2 prime numbers.
8815 is palindromic in (at least) the following bases: 78, -25, and -27.
8815 in base 24 = f77 and consists of only the digits '7' and 'f'.
8815 in base 26 = d11 and consists of only the digits '1' and 'd'.

The number 8815 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A067701: Numbers n such that phi(n-1) + phi(n+1) = phi(2n).
A067724: a(n) = 5*n^2 + 10*n.
A085249: Terms x of A002977 such that both (x-1)/2 and (x-1)/3 are also terms of A002977.
A160794: Vertex number of a rectangular spiral related to Fibonacci numbers and prime numbers. The distances between nearest edges of the spiral that are parallel to the initial edge are the Fibonacci numbers, while the distances between nearest edges perpendicular to the initial edge are the prime numbers.
A172193: 5*n^2+31*n+1.
A177342: a(n) = (4*n^3-3*n^2+5*n-3)/3.
A191313: Sum of the abscissae of the first returns to the horizontal axis (assumed to be 0 if there are no such returns) in all dispersed Dyck paths of length n (i.e. Motzkin paths of length n with no (1,0) steps at positive heights).
A191834: Numbers n not divisible by 2 or 3 such that k^k == k+1 (mod n) has no nonzero solutions.
A225274: Number of distinct values of the sum of i^2 over 7 realizations of i in 0..n
A255401: Numbers n with the property that its k-th smallest divisor, for all 1 <= k <= tau(n), contains exactly k "1" digits in its binary representation.