Properties of the Number 81213

Eighty-One Thousand Two Hundred Thirteen

Basics

Value: 81212 → 81213 → 81214

Parity: odd

Prime: No

Previous Prime: 81203

Next Prime: 81223

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 3 × 11 × 23 × 107

Divisors: 1, 3, 11, 23, 33, 69, 107, 253, 321, 759

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 10011110100111101

Octal: 236475

Duodecimal: 3ABB9

Hexadecimal: 13d3d

Square: 6595551369

Square Root: 284.9789465907964

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

Indices of primes in sequence defined by A(0) = 77, A(n) = 10·A(n-1) - 3 for n > 0. Numbers n such that (690·10ⁿ + 3)/9 is prime. A56260

a(n) = n!*∑_k=0..n Fibonacci(k)/k!. A111139

Let r(n,k) = if k=0 then n, else r(A081210(n),k-1), then a(n)=r(n, A081212(n)). A81213

G.f. satisfies: A(x) = exp( ∑_n>=1 [∑_k=0..n C(n,k)³ * x^k*A(x)^n-k] * xⁿ/n ). A200212