66728169851 has 16 divisors (see below), whose sum is σ = 76594788864. Its totient is φ = 56945310144.

The previous prime is 66728169791. The next prime is 66728169877. The reversal of 66728169851 is 15896182766.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66728169851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66728169451) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3512360 + ... + 3531306.

It is an arithmetic number, because the mean of its divisors is an integer number (4787174304).

Almost surely, 2^66728169851 is an apocalyptic number.

66728169851 is a deficient number, since it is larger than the sum of its proper divisors (9866619013).

66728169851 is a wasteful number, since it uses less digits than its factorization.

66728169851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21130.

The product of its digits is 8709120, while the sum is 59.

The spelling of 66728169851 in words is "sixty-six billion, seven hundred twenty-eight million, one hundred sixty-nine thousand, eight hundred fifty-one".