163997221 has 4 divisors (see below), whose sum is σ = 165688012. Its totient is φ = 162306432.

The previous prime is 163997191. The next prime is 163997231. The reversal of 163997221 is 122799361.

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 28740321 + 135256900 = 5361^2 + 11630^2 .

It is a cyclic number.

It is not a de Polignac number, because 163997221 - 2⁹ = 163996709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163997231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 845250 + ... + 845443.

It is an arithmetic number, because the mean of its divisors is an integer number (41422003).

Almost surely, 2^163997221 is an apocalyptic number.

It is an amenable number.

163997221 is a deficient number, since it is larger than the sum of its proper divisors (1690791).

163997221 is an equidigital number, since it uses as much as digits as its factorization.

163997221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1690790.

The product of its digits is 40824, while the sum is 40.

The square root of 163997221 is about 12806.1399726850. The cubic root of 163997221 is about 547.3672757098.

The spelling of 163997221 in words is "one hundred sixty-three million, nine hundred ninety-seven thousand, two hundred twenty-one".