66728394445 has 16 divisors (see below), whose sum is σ = 81523894320. Its totient is φ = 52424838144.

The previous prime is 66728394437. The next prime is 66728394457. The reversal of 66728394445 is 54449382766.

It can be written as a sum of positive squares in 8 ways, for example, as 2752786089 + 63975608356 = 52467^2 + 252934^2 .

It is a cyclic number.

It is not a de Polignac number, because 66728394445 - 2³ = 66728394437 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66728394445.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 480174 + ... + 603343.

It is an arithmetic number, because the mean of its divisors is an integer number (5095243395).

Almost surely, 2^66728394445 is an apocalyptic number.

It is an amenable number.

66728394445 is a deficient number, since it is larger than the sum of its proper divisors (14795499875).

66728394445 is a wasteful number, since it uses less digits than its factorization.

66728394445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083744.

The product of its digits is 34836480, while the sum is 58.

The spelling of 66728394445 in words is "sixty-six billion, seven hundred twenty-eight million, three hundred ninety-four thousand, four hundred forty-five".