Properties of the Number 2781

Two Thousand Seven Hundred Eighty-One

Basics

Value: 2780 → 2781 → 2782

Parity: odd

Prime: No

Previous Prime: 2777

Next Prime: 2789

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

Today's Target

2730 Try Today's Challenge

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

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

a(n) is the concatenation of n and 3n. A19551

Triangle, read by rows, where T(n,k) = ∑_j=0..n-k-1 C(j+k,j)*T(n-1,j+k) for n>k>=0 with T(n,n)=1. A101494