Properties of the Number 12381

Twelve Thousand Three Hundred Eighty-One

Basics

Value: 12380 → 12381 → 12382

Parity: odd

Prime: No

Previous Prime: 12379

Next Prime: 12391

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 3 × 4127

Divisors: 1, 3, 4127, 12381

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 11000001011101

Octal: 30135

Duodecimal: 71B9

Hexadecimal: 305d

Square: 153289161

Square Root: 111.26994203287786

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

Triangle T, read by rows, such that T(n,k) equals the (n-k)-th row sum of T^k, where T^k is the k-th power of T as a lower triangular matrix. A91351

Partial sums of A045618. A45889

Number of positive solutions to (x₁)² + (x₂)² + (x₃)² + (x₄)² <= n². A341423

Semiprimes in A103372. A103392

a(n) = ∑_j=1..n ∑_k=1..n φ(j·k). A372633

Expansion of ∑_k>=1 φ(k) * x^k/(1 - x^k)⁴, where φ = Euler totient function (A000010). A309323

Number of isosceles triangles, distinct up to congruence, on a centered hexagonal grid of size n. A241237

Numbers j > 1 at which the absolute difference between log(j)*log(A341651(j)) and the nearest integer reaches a record low. A341652

Number of 8 X n binary arrays without the pattern 0 1 diagonally, vertically, antidiagonally or horizontally. A188559

G.f. A(x) = ∑_n>=0 a(n)*xⁿ satisfies: [∑_n>=0 xⁿ/(1 - xⁿ⁺¹)]³ = ∑_n>=0 a(n)*xⁿ/(1 - xⁿ⁺¹)³. A341374