66909378666 has 64 divisors (see below), whose sum is σ = 152549147520. Its totient is φ = 19415289600.

The previous prime is 66909378629. The next prime is 66909378691. The reversal of 66909378666 is 66687390966.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 66909378597 and 66909378606.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 246685 + ... + 441216.

It is an arithmetic number, because the mean of its divisors is an integer number (2383580430).

Almost surely, 2^66909378666 is an apocalyptic number.

66909378666 is an abundant number, since it is smaller than the sum of its proper divisors (85639768854).

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

66909378666 is a wasteful number, since it uses less digits than its factorization.

66909378666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687991.

The product of its (nonzero) digits is 105815808, while the sum is 66.

The spelling of 66909378666 in words is "sixty-six billion, nine hundred nine million, three hundred seventy-eight thousand, six hundred sixty-six".