161623165791 has 4 divisors (see below), whose sum is σ = 215497554392. Its totient is φ = 107748777192.

The previous prime is 161623165789. The next prime is 161623165811. The reversal of 161623165791 is 197561326161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 197561326161 = 3 ⋅65853775387.

It is not a de Polignac number, because 161623165791 - 2¹ = 161623165789 is a prime.

It is a super-2 number, since 2×161623165791² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161623165791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161623165751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26937194296 + ... + 26937194301.

It is an arithmetic number, because the mean of its divisors is an integer number (53874388598).

Almost surely, 2^161623165791 is an apocalyptic number.

161623165791 is a deficient number, since it is larger than the sum of its proper divisors (53874388601).

161623165791 is an equidigital number, since it uses as much as digits as its factorization.

161623165791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53874388600.

The product of its digits is 408240, while the sum is 48.

The spelling of 161623165791 in words is "one hundred sixty-one billion, six hundred twenty-three million, one hundred sixty-five thousand, seven hundred ninety-one".