165218911281 has 12 divisors (see below), whose sum is σ = 238653766260. Its totient is φ = 110143989600.

The previous prime is 165218911259. The next prime is 165218911283. The reversal of 165218911281 is 182119812561.

165218911281 is a `hidden beast` number, since 1 + 6 + 521 + 8 + 9 + 112 + 8 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 97054056225 + 68164855056 = 311535^2 + 261084^2 .

It is not a de Polignac number, because 165218911281 - 2¹⁰ = 165218910257 is a prime.

It is a super-2 number, since 2×165218911281² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165218911283) 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 in 11 ways as a sum of consecutive naturals, for example, 528055 + ... + 780563.

It is an arithmetic number, because the mean of its divisors is an integer number (19887813855).

Almost surely, 2^165218911281 is an apocalyptic number.

It is an amenable number.

165218911281 is a deficient number, since it is larger than the sum of its proper divisors (73434854979).

165218911281 is a wasteful number, since it uses less digits than its factorization.

165218911281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325216 (or 325213 counting only the distinct ones).

The product of its digits is 69120, while the sum is 45.

The spelling of 165218911281 in words is "one hundred sixty-five billion, two hundred eighteen million, nine hundred eleven thousand, two hundred eighty-one".