165621121049 has 2 divisors, whose sum is σ = 165621121050. Its totient is φ = 165621121048.

The previous prime is 165621121027. The next prime is 165621121069. The reversal of 165621121049 is 940121126561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164118163225 + 1502957824 = 405115^2 + 38768^2 .

It is a cyclic number.

It is not a de Polignac number, because 165621121049 - 2¹⁶ = 165621055513 is a prime.

It is not a weakly prime, because it can be changed into another prime (165621121009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82810560524 + 82810560525.

It is an arithmetic number, because the mean of its divisors is an integer number (82810560525).

Almost surely, 2^165621121049 is an apocalyptic number.

It is an amenable number.

165621121049 is a deficient number, since it is larger than the sum of its proper divisors (1).

165621121049 is an equidigital number, since it uses as much as digits as its factorization.

165621121049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 38.

The spelling of 165621121049 in words is "one hundred sixty-five billion, six hundred twenty-one million, one hundred twenty-one thousand, forty-nine".