66217761728 has 28 divisors (see below), whose sum is σ = 131823421392. Its totient is φ = 33002411520.

The previous prime is 66217761713. The next prime is 66217761733. The reversal of 66217761728 is 82716771266.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 66217761728.

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, 1643525 + ... + 1683332.

Almost surely, 2^66217761728 is an apocalyptic number.

It is an amenable number.

66217761728 is a deficient number, since it is larger than the sum of its proper divisors (65605659664).

66217761728 is a wasteful number, since it uses less digits than its factorization.

66217761728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3327180 (or 3327170 counting only the distinct ones).

The product of its digits is 2370816, while the sum is 53.

The spelling of 66217761728 in words is "sixty-six billion, two hundred seventeen million, seven hundred sixty-one thousand, seven hundred twenty-eight".