28109565856 has 12 divisors (see below), whose sum is σ = 55340707842. Its totient is φ = 14054782912.

The previous prime is 28109565839. The next prime is 28109565857. The reversal of 28109565856 is 65856590182.

It can be written as a sum of positive squares in only one way, i.e., 28050890256 + 58675600 = 167484^2 + 7660^2 .

It is a super-2 number, since 2×28109565856² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28109565797 and 28109565806.

It is not an unprimeable number, because it can be changed into a prime (28109565857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 439211935 + ... + 439211998.

Almost surely, 2^28109565856 is an apocalyptic number.

It is an amenable number.

28109565856 is a deficient number, since it is larger than the sum of its proper divisors (27231141986).

28109565856 is an equidigital number, since it uses as much as digits as its factorization.

28109565856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878423943 (or 878423935 counting only the distinct ones).

The product of its (nonzero) digits is 5184000, while the sum is 55.

The spelling of 28109565856 in words is "twenty-eight billion, one hundred nine million, five hundred sixty-five thousand, eight hundred fifty-six".