28666891969 has 3 divisors (see below), whose sum is σ = 28667061283. Its totient is φ = 28666722656.

The previous prime is 28666891963. The next prime is 28666891973. The reversal of 28666891969 is 96919866682.

The square root of 28666891969 is 169313.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 17364650625 + 11302241344 = 131775^2 + 106312^2 .

It is not a de Polignac number, because 28666891969 - 2⁹ = 28666891457 is a prime.

It is a super-2 number, since 2×28666891969² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28666891898 and 28666891907.

It is not an unprimeable number, because it can be changed into a prime (28666891963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 84657 + ... + 253969.

Almost surely, 2^28666891969 is an apocalyptic number.

28666891969 is the 169313-rd square number.

28666891969 is the 84657-th centered octagonal number.

It is an amenable number.

28666891969 is a deficient number, since it is larger than the sum of its proper divisors (169314).

28666891969 is an frugal number, since it uses more digits than its factorization.

28666891969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338626 (or 169313 counting only the distinct ones).

The product of its digits is 120932352, while the sum is 70.

The spelling of 28666891969 in words is "twenty-eight billion, six hundred sixty-six million, eight hundred ninety-one thousand, nine hundred sixty-nine".