Properties of the Number 12105

Twelve Thousand One Hundred Five

Basics

Value: 12104 → 12105 → 12106

Parity: odd

Prime: No

Previous Prime: 12101

Next Prime: 12107

Digit Sum: 9

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 269

Divisors: 1, 3, 5, 9, 15, 45, 269, 807, 1345, 2421

Polygonal

Triangular: No

Square: No

Pentagonal: Yes

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 10111101001001

Octal: 27511

Duodecimal: 7009

Hexadecimal: 2f49

Square: 146531025

Square Root: 110.02272492535349

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

T(n,k)=1/6 the number of nXk 0..5 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors. A185540

a(n) = 3^{-1+floor((n+1}/3))*A(n), where A(n) = 3·A(n-1) + A(n-2) - A(n-3)/3 with A(0)=A(1)=3, A(2)=11. A216034

Pentagonal numbers (A000326) in which parity of digits alternates. A297644

Numbers k such that 2·R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k. A99410

a(n) = 3·n*(9·n - 1)/2. A268351

Expansion of ∏_k>=1 (1 + x^2·k-1)^k*(3·k-1/2)*(1 + x^2·k)^k*(3·k+1/2). A294839

Floor( φ * (3/2)ⁿ ) where φ = (1+sqrt(5))/2. A81226

Pentagonal numbers divisible by 5. A117793

Pentagonal numbers that are the sum of a nonzero pentagonal number and a nonzero square in at least one way. A134938

a(n) = 25·n² + 5. A158445