28505908809 has 18 divisors (see below), whose sum is σ = 47897684250. Its totient is φ = 16289090496.

The previous prime is 28505908807. The next prime is 28505908813. The reversal of 28505908809 is 90880950582.

It can be written as a sum of positive squares in only one way, i.e., 22608129600 + 5897779209 = 150360^2 + 76797^2 .

It is not a de Polignac number, because 28505908809 - 2¹ = 28505908807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28505908807) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 32319184 + ... + 32320065.

Almost surely, 2^28505908809 is an apocalyptic number.

It is an amenable number.

28505908809 is a deficient number, since it is larger than the sum of its proper divisors (19391775441).

28505908809 is a wasteful number, since it uses less digits than its factorization.

28505908809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64639269 (or 64639259 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 54.

The spelling of 28505908809 in words is "twenty-eight billion, five hundred five million, nine hundred eight thousand, eight hundred nine".