163665221 has 4 divisors (see below), whose sum is σ = 172279200. Its totient is φ = 155051244.

The previous prime is 163665211. The next prime is 163665223. The reversal of 163665221 is 122566361.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 163665221 - 2⁶ = 163665157 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 (163665223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4306961 + ... + 4306998.

It is an arithmetic number, because the mean of its divisors is an integer number (43069800).

Almost surely, 2^163665221 is an apocalyptic number.

It is an amenable number.

163665221 is a deficient number, since it is larger than the sum of its proper divisors (8613979).

163665221 is an equidigital number, since it uses as much as digits as its factorization.

163665221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8613978.

The product of its digits is 12960, while the sum is 32.

The square root of 163665221 is about 12793.1708735559. The cubic root of 163665221 is about 546.9976582601.

The spelling of 163665221 in words is "one hundred sixty-three million, six hundred sixty-five thousand, two hundred twenty-one".