165812218561 has 16 divisors (see below), whose sum is σ = 187721458560. Its totient is φ = 145075432320.

The previous prime is 165812218553. The next prime is 165812218577.

It is a happy number.

165812218561 is nontrivially palindromic in base 10.

165812218561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 165812218561 - 2³ = 165812218553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165812218501) 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 in 15 ways as a sum of consecutive naturals, for example, 730485 + ... + 930178.

It is an arithmetic number, because the mean of its divisors is an integer number (11732591160).

Almost surely, 2^165812218561 is an apocalyptic number.

165812218561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165812218561 is a deficient number, since it is larger than the sum of its proper divisors (21909239999).

165812218561 is a wasteful number, since it uses less digits than its factorization.

165812218561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1661016.

The product of its digits is 230400, while the sum is 46.

The spelling of 165812218561 in words is "one hundred sixty-five billion, eight hundred twelve million, two hundred eighteen thousand, five hundred sixty-one".