Properties of the Number 665

Six Hundred Sixty-Five

Basics

Value: 664 → 665 → 666

Parity: odd

Prime: No

Previous Prime: 661

Next Prime: 673

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 5 × 7 × 19

Divisors: 1, 5, 7, 19, 35, 95, 133, 665

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010011001

Octal: 1231

Duodecimal: 475

Hexadecimal: 299

Square: 442225

Square Root: 25.787593916455254

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

a(n) = n*(n+3)/2. A96

a(n) = 3ⁿ - 2ⁿ. A1047

Antisigma(n): Sum of the numbers less than n that do not divide n. A24816

Exponential Riordan array [1, 1/(2-e^x)-1]. A256893

Number of ways to break {1,2,3,...,n} into sets with equal sums. A35470

Number of integer partitions of n such that it is possible to choose a different prime factor of each part. A370592

a(n) = (n-1)*n*(n+4)/6. A5581

Number of reduced words of length n in the Weyl group D₁₅. A162321

Number of reduced words of length n in the Weyl group D₃₆. A162388

a(0) = 1, a(1) = 4, and a(n) = a(n-1) + a(n-2) for n >= 2. A285