165422821 has 2 divisors, whose sum is σ = 165422822. Its totient is φ = 165422820.

The previous prime is 165422813. The next prime is 165422827. The reversal of 165422821 is 128224561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 148108900 + 17313921 = 12170^2 + 4161^2 .

It is a cyclic number.

It is not a de Polignac number, because 165422821 - 2³ = 165422813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165422827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82711410 + 82711411.

It is an arithmetic number, because the mean of its divisors is an integer number (82711411).

Almost surely, 2^165422821 is an apocalyptic number.

It is an amenable number.

165422821 is a deficient number, since it is larger than the sum of its proper divisors (1).

165422821 is an equidigital number, since it uses as much as digits as its factorization.

165422821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 31.

The square root of 165422821 is about 12861.6803334557. The cubic root of 165422821 is about 548.9487589354.

The spelling of 165422821 in words is "one hundred sixty-five million, four hundred twenty-two thousand, eight hundred twenty-one".