Properties of the Number 20605

Twenty Thousand Six Hundred Five

Basics

Value: 20604 → 20605 → 20606

Parity: odd

Prime: No

Previous Prime: 20599

Next Prime: 20611

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 5 × 13 × 317

Divisors: 1, 5, 13, 65, 317, 1585, 4121, 20605

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000001111101

Octal: 50175

Duodecimal: BB11

Hexadecimal: 507d

Square: 424566025

Square Root: 143.54441821262157

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

Third row of Pascal-(1,5,1) array A081580. A81589

Hypotenuse C of primitive Pythagorean triangles such that perimeters are Averages of twin prime pairs, q=p+1, a=q²-p², c=q²+p², b=2·p*q, s=a+b+c, s-+1 are primes. A155175

Partial sums of usigma(n)²: square of the sum of unitary divisors of n. A74789

Numbers of the form p·q*r where p, q, r are distinct primes congruent to 1 mod 4 such that Legendre(p/q) = Legendre(p/r) = Legendre(q/r) = -1. A323271

Positive numbers y such that y² is of the form x²+(x+409)² with integer x. A160577

Numbers k such that the continued fraction for sqrt(k) has period 49. A20388

Numbers k such that k and k² use only the digits 0, 2, 4, 5 and 6. A136898

Triangle read by rows: T(n,k) is the coefficient A_k in the transformation of 1 + x + x² + ... + xⁿ to the polynomial A_k*(x-3k)^k for 0 <= k <= n. A248978

Centered square numbers which are sphenic numbers. A380882

Smallest nonempty set S containing prime divisors of 6k+8 for each k in S. A20605