66156320323165 has 4 divisors (see below), whose sum is σ = 79387584387804. Its totient is φ = 52925056258528.

The previous prime is 66156320323153. The next prime is 66156320323217. The reversal of 66156320323165 is 56132302365166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18167491127556 + 47988829195609 = 4262334^2 + 6927397^2 .

It is a cyclic number.

It is not a de Polignac number, because 66156320323165 - 2²¹ = 66156318226013 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6615632032312 + ... + 6615632032321.

It is an arithmetic number, because the mean of its divisors is an integer number (19846896096951).

Almost surely, 2^{66156320323165} is an apocalyptic number.

It is an amenable number.

66156320323165 is a deficient number, since it is larger than the sum of its proper divisors (13231264064639).

66156320323165 is a wasteful number, since it uses less digits than its factorization.

66156320323165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13231264064638.

The product of its (nonzero) digits is 3499200, while the sum is 49.

The spelling of 66156320323165 in words is "sixty-six trillion, one hundred fifty-six billion, three hundred twenty million, three hundred twenty-three thousand, one hundred sixty-five".