165005221 has 2 divisors, whose sum is σ = 165005222. Its totient is φ = 165005220.

The previous prime is 165005189. The next prime is 165005227. The reversal of 165005221 is 122500561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 132572196 + 32433025 = 11514^2 + 5695^2 .

It is a cyclic number.

It is not a de Polignac number, because 165005221 - 2⁵ = 165005189 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 165005192 and 165005201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165005227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82502610 + 82502611.

It is an arithmetic number, because the mean of its divisors is an integer number (82502611).

Almost surely, 2^165005221 is an apocalyptic number.

It is an amenable number.

165005221 is a deficient number, since it is larger than the sum of its proper divisors (1).

165005221 is an equidigital number, since it uses as much as digits as its factorization.

165005221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 165005221 is about 12845.4358042069. The cubic root of 165005221 is about 548.4864402681.

Adding to 165005221 its reverse (122500561), we get a palindrome (287505782).

The spelling of 165005221 in words is "one hundred sixty-five million, five thousand, two hundred twenty-one".