165208221 has 8 divisors (see below), whose sum is σ = 244752960. Its totient is φ = 110138796.

The previous prime is 165208217. The next prime is 165208237. The reversal of 165208221 is 122802561.

It is a happy number.

165208221 is a `hidden beast` number, since 1 + 652 + 0 + 8 + 2 + 2 + 1 = 666.

165208221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165208221 - 2² = 165208217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 6118823 = 165208221 / (1 + 6 + 5 + 2 + 0 + 8 + 2 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165208291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3059385 + ... + 3059438.

It is an arithmetic number, because the mean of its divisors is an integer number (30594120).

Almost surely, 2^165208221 is an apocalyptic number.

It is an amenable number.

165208221 is a deficient number, since it is larger than the sum of its proper divisors (79544739).

165208221 is an equidigital number, since it uses as much as digits as its factorization.

165208221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6118832 (or 6118826 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 165208221 is about 12853.3350146956. The cubic root of 165208221 is about 548.7112758169.

The spelling of 165208221 in words is "one hundred sixty-five million, two hundred eight thousand, two hundred twenty-one".