Properties of the Number 1281

One Thousand Two Hundred Eighty-One

Basics

Value: 1280 → 1281 → 1282

Parity: odd

Prime: No

Previous Prime: 1279

Next Prime: 1283

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 61

Divisors: 1, 3, 7, 21, 61, 183, 427, 1281

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10100000001

Octal: 2401

Duodecimal: 8A9

Hexadecimal: 501

Square: 1640961

Square Root: 35.79106033634656

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

Moser-de Bruijn sequence: sums of distinct powers of 4. A695

Octagonal numbers: n*(3·n-2). Also called star numbers. A567

Generalized octagonal numbers: k*(3·k-2), k=0, +- 1, +- 2, +-3, ... A1082

a(n) = ∑_k=1..n n/gcd(n,k). A57660

Sum of divisors of square numbers. A65764

Square array, read by antidiagonals, where row n equals the crystal ball sequence for the A_n lattice. A108625

Number of integer partitions of n that are empty, (1), or have at least two parts and these parts are pairwise coprime. A327516

Number of sublattices of index n in generic 3-dimensional lattice. A1001

Triangular numbers plus quarter squares: n*(n+1)/2 + floor(n²/4) (i.e., A000217(n) + A002620(n)). A6578

V-toothpick (or honeycomb) sequence (see Comments lines for definition). A161206