16668538778 has 8 divisors (see below), whose sum is σ = 25004736180. Its totient is φ = 8333626720.

The previous prime is 16668538751. The next prime is 16668538781. The reversal of 16668538778 is 87783586661.

It can be written as a sum of positive squares in 2 ways, for example, as 10427064769 + 6241474009 = 102113^2 + 79003^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288233 + ... + 341196.

Almost surely, 2^16668538778 is an apocalyptic number.

16668538778 is a deficient number, since it is larger than the sum of its proper divisors (8336197402).

16668538778 is a wasteful number, since it uses less digits than its factorization.

16668538778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642672.

The product of its digits is 81285120, while the sum is 65.

The spelling of 16668538778 in words is "sixteen billion, six hundred sixty-eight million, five hundred thirty-eight thousand, seven hundred seventy-eight".