Properties of the Number 20665

Twenty Thousand Six Hundred Sixty-Five

Basics

Value: 20664 → 20665 → 20666

Parity: odd

Prime: No

Previous Prime: 20663

Next Prime: 20681

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 5 × 4133

Divisors: 1, 5, 4133, 20665

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000010111001

Octal: 50271

Duodecimal: BB61

Hexadecimal: 50b9

Square: 427042225

Square Root: 143.75326083258076

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

Centered 24-gonal numbers. A69190

Semiprimes in A054556. A113693

Numbers k such that k concatenated with itself gives the product of two numbers which differ by 8. A116161

Numbers k such that k concatenated with k+7 gives the product of two numbers which differ by 6. A116208

Let p = n-th prime == 7 mod 8; a(n) = sum of quadratic residues mod p that are > p/2. A282040

Number of connected graphs with n edges embeddable into square lattice. A181528

Numbers k such that the continued fraction for sqrt(k) has period 83. A20422

a(n) = a(n-1) + a(n-2) + 7 where a(0) = a(1) = 1. A111733

Number of (n+1) X 3 binary arrays with rows and columns in nondecreasing order and with no 2 X 2 subblock sum differing from a horizontal or vertical neighbor subblock sum by more than one. A184064

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 438", based on the 5-celled von Neumann neighborhood. A272219