27781665864 has 32 divisors (see below), whose sum is σ = 69552168000. Its totient is φ = 9247488192.

The previous prime is 27781665851. The next prime is 27781665869. The reversal of 27781665864 is 46856618772.

It is a junction number, because it is equal to n+sod(n) for n = 27781665798 and 27781665807.

It is not an unprimeable number, because it can be changed into a prime (27781665869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 799324 + ... + 833355.

It is an arithmetic number, because the mean of its divisors is an integer number (2173505250).

Almost surely, 2^27781665864 is an apocalyptic number.

27781665864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

27781665864 is an abundant number, since it is smaller than the sum of its proper divisors (41770502136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

27781665864 is a wasteful number, since it uses less digits than its factorization.

27781665864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1633397 (or 1633393 counting only the distinct ones).

The product of its digits is 27095040, while the sum is 60.

The spelling of 27781665864 in words is "twenty-seven billion, seven hundred eighty-one million, six hundred sixty-five thousand, eight hundred sixty-four".