165936808781 has 4 divisors (see below), whose sum is σ = 166003910652. Its totient is φ = 165869706912.

The previous prime is 165936808777. The next prime is 165936808813. The reversal of 165936808781 is 187808639561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 114148703881 + 51788104900 = 337859^2 + 227570^2 .

It is a cyclic number.

It is not a de Polignac number, because 165936808781 - 2² = 165936808777 is a prime.

It is a super-2 number, since 2×165936808781² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165936808771) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33547226 + ... + 33552171.

It is an arithmetic number, because the mean of its divisors is an integer number (41500977663).

Almost surely, 2^165936808781 is an apocalyptic number.

It is an amenable number.

165936808781 is a deficient number, since it is larger than the sum of its proper divisors (67101871).

165936808781 is an equidigital number, since it uses as much as digits as its factorization.

165936808781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67101870.

The product of its (nonzero) digits is 17418240, while the sum is 62.

The spelling of 165936808781 in words is "one hundred sixty-five billion, nine hundred thirty-six million, eight hundred eight thousand, seven hundred eighty-one".