Properties of the Number 55

Fifty-Five

Basics

Value: 54 → 55 → 56

Parity: odd

Prime: No

Previous Prime: 53

Next Prime: 59

Digit Sum: 10

Digital Root: 1

Palindrome: Yes

Factorization: 5 × 11

Divisors: 1, 5, 11, 55

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: Yes

Tetrahedral: No

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Representations

Binary: 110111

Octal: 67

Duodecimal: 47

Hexadecimal: 37

Square: 3025

Square Root: 7.416198487095663

Classification

Fibonacci: Yes

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

Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1. A45

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

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

Pascal's triangle read by rows: C(n,k) = binomial(n,k) = n!/(k!*(n-k)!), 0 <= k <= n. A7318

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

Semiprimes (or biprimes): products of two primes. A1358

The odd numbers: a(n) = 2·n + 1. A5408

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

a(n) = n' = arithmetic derivative of n: a(0) = a(1) = 0, a(prime) = 1, a(m·n) = m·a(n) + n·a(m). A3415

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

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