28028525921 has 4 divisors (see below), whose sum is σ = 30576573744. Its totient is φ = 25480478100.

The previous prime is 28028525881. The next prime is 28028526007. The reversal of 28028525921 is 12952582082.

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.

It is not a de Polignac number, because 28028525921 - 2²² = 28024331617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28028525321) 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, 1274023895 + ... + 1274023916.

It is an arithmetic number, because the mean of its divisors is an integer number (7644143436).

Almost surely, 2^28028525921 is an apocalyptic number.

It is an amenable number.

28028525921 is a deficient number, since it is larger than the sum of its proper divisors (2548047823).

28028525921 is a wasteful number, since it uses less digits than its factorization.

28028525921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2548047822.

The product of its (nonzero) digits is 230400, while the sum is 44.

The spelling of 28028525921 in words is "twenty-eight billion, twenty-eight million, five hundred twenty-five thousand, nine hundred twenty-one".