Properties of the Number 66

Sixty-Six

Basics

Value: 65 → 66 → 67

Parity: even

Prime: No

Previous Prime: 61

Next Prime: 67

Digit Sum: 12

Digital Root: 3

Palindrome: Yes

Factorization: 2 × 3 × 11

Divisors: 1, 2, 3, 6, 11, 22, 33, 66

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: Yes

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1000010

Octal: 102

Duodecimal: 56

Hexadecimal: 42

Square: 4356

Square Root: 8.12403840463596

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

Triangular numbers: a(n) = binomial(n+1,2) = n*(n+1)/2 = 0 + 1 + 2 + ... + n. A217

Euler totient function φ(n): count numbers <= n and prime to n. A10

The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous. A27

Squarefree numbers: numbers that are not divisible by a square greater than 1. A5117

Largest squarefree number dividing n: the squarefree kernel of n, rad(n), radical of n. A7947

The composite numbers: numbers n of the form x·y for x > 1 and y > 1. A2808

The nonnegative integers. A1477

Palindromes in base 10. A2113

The nonnegative even numbers: a(n) = 2n. A5843

Read n backwards (referred to as R(n) in many sequences). A4086

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