1

Notation

1 can be expressed in many ways apart from the usual decimal (base-10) notation. It can be written out in wordswith formatting and even extra punctuation added depending on the language. In more technical situationsnumbers are commmonly expressed in scientific notation or in different base systems such as binary or hex.

• Written form in US english: ‘One’
• Written form in British english: ‘One’
• Scientific notation: 1 × 10⁰
• Binary (base-2): 1₂
• Octal (base-8): 1₈
• Hexadecimal (base-16): 0x1
• Base-36: 1

Prime factorization of 1

Prime factors are the prime numbers that multiply together to form that number. You could say that a number is made or ‘composed’ of its prime factors. Every whole number greater than one is formed from at least one prime factor. (Prime numbers have only one prime factor: themselves.)

Calculating the prime factors of a number is known as prime factorization. For very large numbers this can be a challenging task.

How many prime factors does 1 have?

It has zero distinct prime factors.

• Number of distinct prime factors ω(n): 0
• Total number of prime factors including multiple instances Ω(n): 0

Divisors of 1

Divisors are the numbers that divide a given number exactlywith no remainder.

How many divisors does 1 have?

In totalit has one divisors (including one and itself). Not including itselfit has zero proper divisors.

• Number of divisors d(n): 1
• Number of proper divisors τ(n)−1: 0

• List of divisors. Here is the complete set:

  1
• Sum of all divisors σ(n): 1
• Sum of proper divisors (its aliquot sum) s(n): 0
• 1 is a ‘deficient’ (or ‘defective’) numberbecause the sum of its proper divisors (0) is less than itself. Its deficiency is 1

Roots and squares of 1

Roots of a number are numbers thatwhen multiplied by themselves a certain number of timesgive the original number. For examplethe square root of four is twobecause 2 × 2 = 4.

Squares are numbers obtained by multiplying a number by itself a certain number of times.

• 1 squared (1²) is 1
• 1 cubed (1³) is 1
• The square root of 1 is 1

  As the square root is an exact integer with no fractional partthat means 1 is a perfect square number.

• The cube root of 1 is 1

  As the cube root is an exact integer with no fractional partthat means 1 is a perfect cube number.

• Being both a perfect square and a perfect cube1 is also a perfect sixth number.

Scales and comparisons

How big is 1? The following comparisons will give you some idea.

• A solid cube with a volume of 1 cubic inches would be around 1 inches high.

Fun! Recreational maths with 1

• 1 is the same when its digits are reversed. That makes it a palindromic number!
• It has 1 decimal digits.
• If you add the digits together you get 1
• 1 is exactly divisible by the sum of its digits (1) in base 10. That means 1 is a Harshad number (aka Niven number).
• More fun facts coming soon.

Related numbers

Numbers related to 1.

• The next prime number is 2
• 1 doubled equals 2

About this page

Data compiled by the Numbermatics team.

Page content last reviewed: 5 February 2026. Mathematical properties verified on 5 February 2026.