28667489581 has 4 divisors (see below), whose sum is σ = 28667846592. Its totient is φ = 28667132572.

The previous prime is 28667489569. The next prime is 28667489597. The reversal of 28667489581 is 18598476682.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18598476682 = 2 ⋅9299238341.

It is a cyclic number.

It is not a de Polignac number, because 28667489581 - 2²⁹ = 28130618669 is a prime.

It is a super-2 number, since 2×28667489581² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28667489561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4446 + ... + 239488.

It is an arithmetic number, because the mean of its divisors is an integer number (7166961648).

Almost surely, 2^28667489581 is an apocalyptic number.

It is an amenable number.

28667489581 is a deficient number, since it is larger than the sum of its proper divisors (357011).

28667489581 is a wasteful number, since it uses less digits than its factorization.

28667489581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357010.

The product of its digits is 46448640, while the sum is 64.

The spelling of 28667489581 in words is "twenty-eight billion, six hundred sixty-seven million, four hundred eighty-nine thousand, five hundred eighty-one".