16391686664 has 8 divisors (see below), whose sum is σ = 30734412510. Its totient is φ = 8195843328.

The previous prime is 16391686643. The next prime is 16391686679. The reversal of 16391686664 is 46668619361.

It can be written as a sum of positive squares in only one way, i.e., 11504278564 + 4887408100 = 107258^2 + 69910^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1024480409 + ... + 1024480424.

Almost surely, 2^16391686664 is an apocalyptic number.

It is an amenable number.

16391686664 is a deficient number, since it is larger than the sum of its proper divisors (14342725846).

16391686664 is a wasteful number, since it uses less digits than its factorization.

16391686664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2048960839 (or 2048960835 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 56.

The spelling of 16391686664 in words is "sixteen billion, three hundred ninety-one million, six hundred eighty-six thousand, six hundred sixty-four".