69 (number)
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69 is a natural number between consecutive integers. It is greater than 68 and less than 70. In the decimal (base 10) system, it consists of two digits: 6 and 9.
69 is a composite number, meaning it has divisors other than 1 and itself. Its divisors are 1, 3, 23, and 69. Its prime factorization is 3 × 23. Therefore, 69 is not a prime number.
Mathematical properties
69 is an odd number, as it cannot be divided by 2. The sum of its proper divisors (1 + 3 + 23) is 27, which is less than 69; therefore it is a deficient number. It is also a semiprime, being the product of two distinct prime numbers.
When written in other base systems, its form changes. For example, in the binary (base 2) system, 69 is written as 1000101. This representation is palindromic—it reads the same in both directions.
General usage
69 appears in everyday contexts: years (such as 1969 or 2069, abbreviated as '69), road numbers, and group or staff counts. In these cases the number serves only as an identifier, not as a mathematically significant property.
Because the digits of 69 appear identical when rotated 180 degrees, the number is classified as strobogrammatic—a number whose form does not change when rotated.