Properties of the Number 80820

Eighty Thousand Eight Hundred Twenty

Basics

Value: 80819 → 80820 → 80821

Parity: even

Prime: No

Previous Prime: 80819

Next Prime: 80831

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 2 ² × 3 ² × 5 × 449

Divisors: 1, 2, 3, 4, 5, 6, 9, 10, 12, 15

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011101110110100

Octal: 235664

Duodecimal: 3A930

Hexadecimal: 13bb4

Square: 6531872400

Square Root: 284.2885857715712

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 (n+2) X (k+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 1 2 4 6 or 7. A252558

a(1) = 1; for n>1, sum of binomial(n,k) as k runs over RRS(n), the reduced residue system of n. A56188

Array read by diagonals downwards: A(n,k) for n>=2 and k>=0 is the number of (n,k)-polyominoes. A381030

Number of (n,1)-polyominoes. A286344

Number of (n+2)X(4+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3X3 column and antidiagonal sum not equal to 1 2 4 6 or 7. A252554

Number of (5+2)X(n+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3X3 column and antidiagonal sum not equal to 1 2 4 6 or 7. A252563

Table read by antidiagonals: T(n,k) (n >= 3, k >= 0) is the number of cells in a regular n-gon after k generations of mitosis. A350000

Least m such that m² >= n*(n+1)/2. A80820