Properties of the Number 809

Eight Hundred Nine

Basics

Value: 808 → 809 → 810

Parity: odd

Prime: Yes

Previous Prime: 797

Next Prime: 811

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 809

Divisors: 1, 809

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1100101001

Octal: 1451

Duodecimal: 575

Hexadecimal: 329

Square: 654481

Square Root: 28.442925306655784

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

Lesser of twin primes. A1359

Primes of the form x² + xy + 2y², with·and y nonnegative. A106856

Sophie Germain primes p: 2p+1 is also prime. A5384

Primes of the form 2x² + 2xy + 17y². A139827

Primes of form 8n+1, that is, primes congruent to 1 mod 8. A7519

Number of flat partitions of n: partitions {a_i} with each |a_i - a_i-1| <= 1. A34296

Primes of form 10·k + 9. A30433

Irregular primes: primes p such that at least one of the numerators of the Bernoulli numbers B₂, B₄, ..., B_p-3 (A000367) is divisible by p. A928

Number of steps until the RADD sequence T(k+1) = n + R(T(k)), T(0) = 1, enters a cycle; -1 if no cycle is ever reached. (R=A004086: reverse digits). A117816

The "comma sequence": the lexicographically earliest sequence of positive numbers with the property that the sequence formed by the pairs of digits adjacent to the commas between the terms is the same as the sequence of successive differences between the terms. A121805