165200555521 has 2 divisors, whose sum is σ = 165200555522. Its totient is φ = 165200555520.

The previous prime is 165200555519. The next prime is 165200555579. The reversal of 165200555521 is 125555002561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 93449433025 + 71751122496 = 305695^2 + 267864^2 .

It is a cyclic number.

It is not a de Polignac number, because 165200555521 - 2¹ = 165200555519 is a prime.

Together with 165200555519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (165200555591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82600277760 + 82600277761.

It is an arithmetic number, because the mean of its divisors is an integer number (82600277761).

Almost surely, 2^165200555521 is an apocalyptic number.

It is an amenable number.

165200555521 is a deficient number, since it is larger than the sum of its proper divisors (1).

165200555521 is an equidigital number, since it uses as much as digits as its factorization.

165200555521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 75000, while the sum is 37.

The spelling of 165200555521 in words is "one hundred sixty-five billion, two hundred million, five hundred fifty-five thousand, five hundred twenty-one".