165691781031 has 16 divisors (see below), whose sum is σ = 257635424000. Its totient is φ = 94681017144.

The previous prime is 165691781029. The next prime is 165691781041. The reversal of 165691781031 is 130187196561.

It is not a de Polignac number, because 165691781031 - 2¹ = 165691781029 is a prime.

It is a super-2 number, since 2×165691781031² (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 (165691781041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80510041 + ... + 80512098.

It is an arithmetic number, because the mean of its divisors is an integer number (16102214000).

Almost surely, 2^165691781031 is an apocalyptic number.

165691781031 is a deficient number, since it is larger than the sum of its proper divisors (91943642969).

165691781031 is an equidigital number, since it uses as much as digits as its factorization.

165691781031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161022163 (or 161022149 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 48.

The spelling of 165691781031 in words is "one hundred sixty-five billion, six hundred ninety-one million, seven hundred eighty-one thousand, thirty-one".