Welcome to the Number Dictionary!

This website is an informational resource for the fascinating properties of numbers and numeral systems.

Representation numerals
Numeral systems
Binary
Base-3
Base-4
Base-5
Base-6
Septimal
Octal
Duodecimal
Hexadecimal
Vigesimal
Base-24
Base-36
Negabinary
Multi-Polygonal numbers
Triangular
Square
Pentagonal
Hexagonal
Heptagonal
Octogonal
Nonagonal
Decagonal
Special numbers
Primes
Twin primes
Gaussian primes
Fibonacci
Perfect numbers
Abundant numbers
Deficient numbers
Palindromic
Layland
Harshad
Kaprekar
Smith
Sums & other
Difference of 2 squares
Sum of all divisors
Divisors
Factorization
Perfect powers

Begin with a random number: 23, or use the search on the top.

Try these examples: 6 (Perfect) • 12 (Abundant) • 8 (Deficient) • 3 (Twin Prime) • 9 (Nonagonal) • 16 (Fourth Power) • 18 (Harshad) • 45 (Kaprekar) • 4 (Smith)

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