165207221 has 2 divisors, whose sum is σ = 165207222. Its totient is φ = 165207220.

The previous prime is 165207191. The next prime is 165207227. The reversal of 165207221 is 122702561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 159012100 + 6195121 = 12610^2 + 2489^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165207221 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165207227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82603610 + 82603611.

It is an arithmetic number, because the mean of its divisors is an integer number (82603611).

Almost surely, 2^165207221 is an apocalyptic number.

It is an amenable number.

165207221 is a deficient number, since it is larger than the sum of its proper divisors (1).

165207221 is an equidigital number, since it uses as much as digits as its factorization.

165207221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 165207221 is about 12853.2961142269. The cubic root of 165207221 is about 548.7101687041.

Adding to 165207221 its reverse (122702561), we get a palindrome (287909782).

The spelling of 165207221 in words is "one hundred sixty-five million, two hundred seven thousand, two hundred twenty-one".