165765249521 has 2 divisors, whose sum is σ = 165765249522. Its totient is φ = 165765249520.

The previous prime is 165765249491. The next prime is 165765249557. The reversal of 165765249521 is 125942567561.

165765249521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 164401055296 + 1364194225 = 405464^2 + 36935^2 .

It is a cyclic number.

It is not a de Polignac number, because 165765249521 - 2²² = 165761055217 is a prime.

It is not a weakly prime, because it can be changed into another prime (165765249821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82882624760 + 82882624761.

It is an arithmetic number, because the mean of its divisors is an integer number (82882624761).

Almost surely, 2^165765249521 is an apocalyptic number.

It is an amenable number.

165765249521 is a deficient number, since it is larger than the sum of its proper divisors (1).

165765249521 is an equidigital number, since it uses as much as digits as its factorization.

165765249521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536000, while the sum is 53.

The spelling of 165765249521 in words is "one hundred sixty-five billion, seven hundred sixty-five million, two hundred forty-nine thousand, five hundred twenty-one".