Properties of the Number 2128

Two Thousand One Hundred Twenty-Eight

Basics

Value: 2127 → 2128 → 2129

Parity: even

Prime: No

Previous Prime: 2113

Next Prime: 2129

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 ⁴ × 7 × 19

Divisors: 1, 2, 4, 7, 8, 14, 16, 19, 28, 38

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100001010000

Octal: 4120

Duodecimal: 1294

Hexadecimal: 850

Square: 4528384

Square Root: 46.130250378683186

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

Number of (w,x,y) such that w,x,y are all in {0,...,n} and |w-x| = |x-y|. A212959

a(n) = a(n-1) + a(n-2) + a(n-3) with a(0) = 1, a(1) = a(2) = 2. A214727

a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-1)*a(1) for n >= 3. A25227

G.f.: ∏_{n >= 0} (1+x²ⁿ⁺¹)/(1-x²ⁿ⁺¹). A80054

Partial sums of primes, if 1 is regarded as a prime (as it was until quite recently, see A008578). A14284

Q-toothpick sequence (see Comments for precise definition). A187210

Preperiod (or threshold) of orbit of Post's {00, 1101} tag system applied to the word (100)ⁿ, or -1 if this word has an unbounded trajectory. A284119

Expansion of 1/((1-x)²*(1-x²)*(1-x³)). A601

Four times pentagonal numbers: a(n) = 2·n*(3·n-1). A33579

Square array read by falling antidiagonals of central polynomial coefficients: largest coefficient in expansion of (1 + x + x² + ... + x^n-1)^k = ((1-xⁿ)/(1-x))^k, i.e., the coefficient of x^floor(k*(n-1)/2) and of x^ceiling(k*(n-1)/2); also number of compositions of floor(k*(n+1)/2) into exactly k positive integers each no more than n. A77042