28311522021 has 12 divisors (see below), whose sum is σ = 41353909740. Its totient is φ = 18662276160.

The previous prime is 28311521939. The next prime is 28311522047. The reversal of 28311522021 is 12022511382.

It can be written as a sum of positive squares in 2 ways, for example, as 8120532996 + 20190989025 = 90114^2 + 142095^2 .

It is not a de Polignac number, because 28311522021 - 2¹⁰ = 28311520997 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28311522061) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17671810 + ... + 17673411.

It is an arithmetic number, because the mean of its divisors is an integer number (3446159145).

Almost surely, 2^28311522021 is an apocalyptic number.

It is an amenable number.

28311522021 is a deficient number, since it is larger than the sum of its proper divisors (13042387719).

28311522021 is a wasteful number, since it uses less digits than its factorization.

28311522021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35345316 (or 35345313 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The spelling of 28311522021 in words is "twenty-eight billion, three hundred eleven million, five hundred twenty-two thousand, twenty-one".