168816321 has 6 divisors (see below), whose sum is σ = 243845810. Its totient is φ = 112544208.

The previous prime is 168816317. The next prime is 168816353. The reversal of 168816321 is 123618861.

168816321 is a `hidden beast` number, since 16 + 8 + 8 + 1 + 632 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 167340096 + 1476225 = 12936^2 + 1215^2 .

It is not a de Polignac number, because 168816321 - 2² = 168816317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (168816301) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9378676 + ... + 9378693.

Almost surely, 2^168816321 is an apocalyptic number.

It is an amenable number.

168816321 is a deficient number, since it is larger than the sum of its proper divisors (75029489).

168816321 is a wasteful number, since it uses less digits than its factorization.

168816321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18757375 (or 18757372 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 168816321 is about 12992.9335024851. The cubic root of 168816321 is about 552.6771089892.

The spelling of 168816321 in words is "one hundred sixty-eight million, eight hundred sixteen thousand, three hundred twenty-one".