28320772565 has 4 divisors (see below), whose sum is σ = 33984927084. Its totient is φ = 22656618048.

The previous prime is 28320772561. The next prime is 28320772577. The reversal of 28320772565 is 56527702382.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56527702382 = 2 ⋅28263851191.

It can be written as a sum of positive squares in 2 ways, for example, as 16076464849 + 12244307716 = 126793^2 + 110654^2 .

It is a cyclic number.

It is not a de Polignac number, because 28320772565 - 2² = 28320772561 is a prime.

It is a super-4 number, since 4×28320772565⁴ (a number of 43 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28320772561) 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, 2832077252 + ... + 2832077261.

It is an arithmetic number, because the mean of its divisors is an integer number (8496231771).

Almost surely, 2^28320772565 is an apocalyptic number.

It is an amenable number.

28320772565 is a deficient number, since it is larger than the sum of its proper divisors (5664154519).

28320772565 is an equidigital number, since it uses as much as digits as its factorization.

28320772565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5664154518.

The product of its (nonzero) digits is 1411200, while the sum is 47.

The spelling of 28320772565 in words is "twenty-eight billion, three hundred twenty million, seven hundred seventy-two thousand, five hundred sixty-five".