Properties of the Number -2781

Seven Hundred Eighty-One

Basics

Value: -2782 → -2781 → -2780

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ³ × 103

Divisors: 1, 3, 9, 27, 103, 309, 927, 2781

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -101011011101

Octal: -5335

Duodecimal: -1739

Hexadecimal: -add

Square: 7733961

Square Root: 52.73518749374084

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 of coefficients T(n,k) in g.f. A(x,y) satisfying ∑_n=-oo..+oo (-1)ⁿ * (xⁿ + y·A(x,y))ⁿ = 1 + (y+2)*∑_n>=1 (-1)ⁿ * x^n², for n >= 1, as read by rows. A370040

Values of n such that L(3) and N(3) are both prime, where L(k) = (n²+n+1)*2^2·k + (2·n+1)*2^k + 1, N(k) = (n²+n+1)*2^k + n. A226923

Number of partitions of n into at most 1 copy of 1, 2 copies of 2, 3 copies of 3, ... . A52335

a(n) = n·prime(n). A33286

a(n) = ∑_k=0..n (n-k+1)^k. A26898

L-toothpick sequence (see Comment lines for definition). A172310

Numbers m such that there are precisely 13 groups of order m. A292896

Number A(n,k) of set partitions of [n] such that all absolute differences between least elements of consecutive blocks are <= k; square array A(n,k), n>=0, k>=0, read by antidiagonals. A287216

Consider Post's tag system applied to the word (100)ⁿ; a(n) = position of the longest word in the orbit, or -1 if the orbit is unbounded. A291796

Numbers k such that k¹⁰ is an interprime = average of two successive primes. A75233