Properties of the Number 20641

Twenty Thousand Six Hundred Forty-One

Basics

Value: 20640 → 20641 → 20642

Parity: odd

Prime: Yes

Previous Prime: 20639

Next Prime: 20663

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 20641

Divisors: 1, 20641

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000010100001

Octal: 50241

Duodecimal: BB41

Hexadecimal: 50a1

Square: 426050881

Square Root: 143.6697602141801

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

Triangle read by rows: Zig-zag Eulerian number triangle T(n, k). A205497

Primes that divide at least one term of Sylvester's sequence s = A000058: s(n+1) = s(n)² - s(n) + 1, s(0) = 2. A7996

Primes p for which the period of reciprocal = (p-1)/8. A56213

Greatest prime factor of n⁵ + 1. A240548

Consider all ways of writing a number as p+2m² where p is 1 or a prime and m >= 0; sequence gives numbers that are expressible in at least 2 more ways than any smaller number. A16067

Numbers k such that k, k+1, k+2 and k+3 are 1,2,3,4-almost primes. A113000

Least k such that the difference between consecutive semiprimes A065516(k) equals n, or 0 if no such k exists. A123375

Largest prime divisor of Lucas(5·n), where Lucas(k) = A000032(k). A121171

E.g.f. A(x) satisfies A(x) = exp( x * (1+x²)² * A(x)² ). A390060

a(n) = 5·a(n-2) + 2·a(n-3). A135138