163398721 has 2 divisors, whose sum is σ = 163398722. Its totient is φ = 163398720.

The previous prime is 163398707. The next prime is 163398769. The reversal of 163398721 is 127893361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142468096 + 20930625 = 11936^2 + 4575^2 .

It is an emirp because it is prime and its reverse (127893361) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 163398721 - 2⁷ = 163398593 is a prime.

It is not a weakly prime, because it can be changed into another prime (163318721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81699360 + 81699361.

It is an arithmetic number, because the mean of its divisors is an integer number (81699361).

Almost surely, 2^163398721 is an apocalyptic number.

It is an amenable number.

163398721 is a deficient number, since it is larger than the sum of its proper divisors (1).

163398721 is an equidigital number, since it uses as much as digits as its factorization.

163398721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 163398721 is about 12782.7509167628. The cubic root of 163398721 is about 546.7006005028.

The spelling of 163398721 in words is "one hundred sixty-three million, three hundred ninety-eight thousand, seven hundred twenty-one".