28128344257 has 16 divisors (see below), whose sum is σ = 31092158160. Its totient is φ = 25281331200.

The previous prime is 28128344239. The next prime is 28128344261. The reversal of 28128344257 is 75244382182.

It can be written as a sum of positive squares in 8 ways, for example, as 4928180401 + 23200163856 = 70201^2 + 152316^2 .

It is a cyclic number.

It is not a de Polignac number, because 28128344257 - 2²³ = 28119955649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28128344957) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 219457 + ... + 323137.

It is an arithmetic number, because the mean of its divisors is an integer number (1943259885).

Almost surely, 2^28128344257 is an apocalyptic number.

It is an amenable number.

28128344257 is a deficient number, since it is larger than the sum of its proper divisors (2963813903).

28128344257 is a wasteful number, since it uses less digits than its factorization.

28128344257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104244.

The product of its digits is 860160, while the sum is 46.

The spelling of 28128344257 in words is "twenty-eight billion, one hundred twenty-eight million, three hundred forty-four thousand, two hundred fifty-seven".