22222222

22222222 is a decimal numeral consisting of eight consecutive digits, all equal to 2. The value in base-10 is 22,222,222. It is a palindromic number, meaning it reads the same forwards and backwards, and it is also a repdigit, a number formed by repeating a single digit.

In mathematical terms, 22,222,222 is an even, composite integer. Its prime factorization is 2 × 11 × 73 × 101 × 137, showing that it has several small prime factors. Equivalently, 22,222,222 = 2 × 11,111,111, where 11,111,111 is the repunit with eight ones, equal to (10^8 − 1)/9. The factorization of 11,111,111 into 11 × 101 × 73 × 137 explains the full prime decomposition of 22,222,222.

As a number with eight identical digits, it is often cited in discussions of repdigits and palindromic numbers. Its magnitude places it in the tens of millions, specifically about 2.2 × 10^7.

See also: repunit, repdigit, palindromic number.