Properties of the Number 685

Six Hundred Eighty-Five

Basics

Value: 684 → 685 → 686

Parity: odd

Prime: No

Previous Prime: 683

Next Prime: 691

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 5 × 137

Divisors: 1, 5, 137, 685

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 1010101101

Octal: 1255

Duodecimal: 491

Hexadecimal: 2ad

Square: 469225

Square Root: 26.1725046566048

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 square numbers: a(n) = 2·n*(n+1)+1. Sums of two consecutive squares. Also, consider all Pythagorean triples (X, Y, Z=Y+1) ordered by increasing Z; then sequence gives Z values. A1844

a(n) = ceiling(n²/2). A982

Number of strict integer partitions of n with pairwise indivisible parts. A303362

Coordination sequence for 3D uniform tiling formed by stacking parallel layers of the 4.8.8 2D tiling (cf. A008576). A299259

Number of strict partitions of 2n that include a partition of n. A237258

Numbers m such that the Bernoulli number B_2·m has denominator 66. A51229

Expansion of 1/(x¹⁰+x⁹-x⁷-x⁶-x⁵-x⁴-x³+x+1) (inverse of Salem polynomial). A29826

Numerator of ∑_k=0..n 1/k!. A61354

Numbers whose sum of digits is 19. A166459

Hypotenuses for which there exist exactly 4 distinct integer triangles. A84648