66440651604 has 12 divisors (see below), whose sum is σ = 155028187104. Its totient is φ = 22146883864.

The previous prime is 66440651573. The next prime is 66440651623. The reversal of 66440651604 is 40615604466.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2768360472 + ... + 2768360495.

It is an arithmetic number, because the mean of its divisors is an integer number (12919015592).

Almost surely, 2^66440651604 is an apocalyptic number.

It is an amenable number.

66440651604 is an abundant number, since it is smaller than the sum of its proper divisors (88587535500).

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

66440651604 is a wasteful number, since it uses less digits than its factorization.

66440651604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5536720974 (or 5536720972 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 42.

The spelling of 66440651604 in words is "sixty-six billion, four hundred forty million, six hundred fifty-one thousand, six hundred four".