28888634921 has 4 divisors (see below), whose sum is σ = 28889032452. Its totient is φ = 28888237392.

The previous prime is 28888634897. The next prime is 28888634923. The reversal of 28888634921 is 12943688882.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12943688882 = 2 ⋅6471844441.

It can be written as a sum of positive squares in 2 ways, for example, as 7980920896 + 20907714025 = 89336^2 + 144595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28888634921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28888634923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55190 + ... + 246623.

It is an arithmetic number, because the mean of its divisors is an integer number (7222258113).

Almost surely, 2^28888634921 is an apocalyptic number.

It is an amenable number.

28888634921 is a deficient number, since it is larger than the sum of its proper divisors (397531).

28888634921 is an equidigital number, since it uses as much as digits as its factorization.

28888634921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397530.

The product of its digits is 10616832, while the sum is 59.

The spelling of 28888634921 in words is "twenty-eight billion, eight hundred eighty-eight million, six hundred thirty-four thousand, nine hundred twenty-one".