111111

111111 is the decimal numeral consisting of six consecutive digits '1'. In mathematics, it is commonly referred to as a repunit of length six in base 10, often denoted R6. The value of 111111 is 111,111, which can be expressed as (10^6 − 1)/9.

As a number, 111,111 is composite and has the prime factorization 3 × 7 × 11 × 13 × 37. It is a palindrome, and it is divisible by 3 and 11, among other factors, but it is not divisible by 9 since the sum of its digits is 6. The factorization illustrates a common property of repunits in base 10, where longer repunits split into products of small primes.

In broader mathematical context, repunits are numbers composed exclusively of the digit 1 in a given base. In base 10, R6 serves as an example of how such numbers can be factored and how their divisibility patterns relate to the structure of repunits in general. The number also highlights that a string of ones can encode interesting arithmetic relationships, such as divisibility by 11 through the alternating-sum test and by 37 via division into a shorter repunit.

Beyond pure math, strings like "111111" frequently appear in computer tests, data samples, or demonstrations as simple, uniform digit sequences. They are not tied to a widely recognized historical event or cultural phenomenon, but they are commonly used as convenient test data or illustrative examples in numerical contexts. See also repunit, palindromic number, and numeral systems.