Properties of the Number 20978

Twenty Thousand Nine Hundred Seventy-Eight

Basics

Value: 20977 → 20978 → 20979

Parity: even

Prime: No

Previous Prime: 20963

Next Prime: 20981

Digit Sum: 26

Digital Root: 8

Palindrome: No

Factorization: 2 × 17 × 617

Divisors: 1, 2, 17, 34, 617, 1234, 10489, 20978

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000111110010

Octal: 50762

Duodecimal: 10182

Hexadecimal: 51f2

Square: 440076484

Square Root: 144.83784035948617

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

T(n,k)=Number of -k..k arrays x(0..n-1) of n elements with zero sum and elements alternately strictly increasing and strictly decreasing. A200057

Compositions with superdiagonal growth: number of compositions (p0, p1, p2, ...) of n with π - p0 >= i. A238861

n such that A205592(n) > n. A205594

Least k such that A205592(k) = 2ⁿ. A205596

Number of n-bead necklaces labeled with numbers 1..6 not allowing reversal, with no adjacent beads differing by more than 1. A208775

On a spirally numbered square grid, with labels starting at 1, this is the number of the last cell that an (n,n+1) leaper reaches before getting trapped, or -1 if it never gets trapped. A343179

a(0) = 1. a(n+1) = sum{k=0 to n} a(n-k)*a(ceiling(k/2)). A127681

Number of isoscent sequences of length n with maximal number of descents. A243484

Least number·such that xⁿ has n digits equal to k. Case k = 8. A285455

Number of -4..4 arrays X (0..n-1) of n elements with zero sum and elements alternately strictly increasing and strictly decreasing. A200053