Properties of the Number 21728

Twenty-One Thousand Seven Hundred Twenty-Eight

Basics

Value: 21727 → 21728 → 21729

Parity: even

Prime: No

Previous Prime: 21727

Next Prime: 21737

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 2 ⁵ × 7 × 97

Divisors: 1, 2, 4, 7, 8, 14, 16, 28, 32, 56

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010011100000

Octal: 52340

Duodecimal: 106A8

Hexadecimal: 54e0

Square: 472105984

Square Root: 147.40420618150623

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

a(n) = 4·a(n-1) - a(n-2), with a(0) = 0, a(1) = 2. A52530

Number of integer compositions of n into parts that are alternately unequal and equal. A357644

a(2n+1) = a(2n) + a(2n-1), a(2n) = 2·a(2n-1) + a(2n-2); a(n) = n for n = 0, 1. A48788

Limit of the sequence obtained from S(0) = (1,1) and, for n > 0, S(n) = I(S(n-1)), where I consists of inserting, for i = 1, 2, 3..., the term a(i) + a(i+1) between any two terms for which 7·a(i+1) <= 11·a(i). A82630

a(n) = 14·a(n-1) - a(n-2); a(0) = 0, a(1) = 8. A67900

Maximal term of TRIP-Stern sequence of level n corresponding to permutation triple (e,23,e). A271488

Number of ways to write n as an ordered sum of seven positive Fibonacci numbers (with a single type of 1). A357694

Gaps of 8 in sequence A038593 (lower terms). A38655

Number of partitions of n into distinct parts with boundary size 9. A227566

Number of squares of all sizes in 3·n*(n+1)/2-ominoes in form of three-quarters of Aztec diamonds. A258440