Number 2: Natural number

It is the number after 1 (one) and the number before 3 (three). In Roman numerals, it is II.

← 1 2 3 →
-1 0 1 2 3 4 5 6 7 8 9 → List of numbers — Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	two
Ordinal	2nd (second)
Factorization	prime
Divisors	1, 2
Greek numeral	Β´
Roman numeral	II
Roman numeral (unicode)	Ⅱ, ⅱ
Greek prefix	di-
Latin prefix	duo- bi-
Old English prefix	twi-
Binary	102
Ternary	23
Quaternary	24
Quinary	25
Senary	26
Octal	28
Duodecimal	212
Hexadecimal	216
Vigesimal	220
Base 36	236
Greek numeral	β'
Arabic	٢
Urdu
Ge'ez	፪
Bengali	২
Chinese numeral	二，弍，贰，貳
Devanāgarī	२
Telugu	౨
Tamil	௨
Hebrew	ב (Bet)
Khmer	២
Korean	이，둘
Thai	๒

Two has many meanings in math. For example: ${\displaystyle 1+1=2}$ . An integer is even if half of it equals an integer. If the last digit of a number is even, then the number is even. This means that if you multiply 2 times anything, it will end in 0, 2, 4, 6, or 8.

Two is the smallest, first, and only even prime number. The next prime number is three. Two and three are the only prime numbers next to each other. The even numbers above two are not prime because they are divisible by 2.

Fractions with 2 in the bottom do not yield infinite.

Two is the framework of the binary system used in computers. The binary way is the simplest system of numbers where natural numbers (0-9) can be written.

Two also has the unique property that 2+2 = 2·2 = 2² and 2! + 2 = 2².

Powers of two are important to computer science.

The square root of two was the first known irrational number.