Properties of the Number 81387

Eighty-One Thousand Three Hundred Eighty-Seven

Basics

Value: 81386 → 81387 → 81388

Parity: odd

Prime: No

Previous Prime: 81373

Next Prime: 81401

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 9043

Divisors: 1, 3, 9, 9043, 27129, 81387

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011110111101011

Octal: 236753

Duodecimal: 3B123

Hexadecimal: 13deb

Square: 6623843769

Square Root: 285.2840689558392

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(0)=1, otherwise a(n) = ∑_{k=0..floor((n-1)/2)} binomial(n-k-1,k)*a(n-1-2·k). A172383

Triangle, read by rows, of the coefficients of [x^k] in G100228(x)ⁿ such that the row sums are 4ⁿ-1 for n>0, where G100228(x) is the g.f. of A100228. A100229

Number of idempotent 3X3 -n..n matrices of rank 2. A223452

a(n) = a(n-1) + 3·a(n-2) -2·a(n-3) - 2·a(n-4), where a(0) = 1, a(1) = -2, a(2) = 2, a(3) = 1. A295855

Number of non-unitary prime divisors of central binomial coefficient, C(2n,n) = A000984(n), i.e., number of prime factors in C(2n,n) whose exponent is greater than one. A81387