161854841173 has 4 divisors (see below), whose sum is σ = 165802520268. Its totient is φ = 157907162080.

The previous prime is 161854841167. The next prime is 161854841177. The reversal of 161854841173 is 371148458161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 371148458161 = 13 ⋅28549881397.

It can be written as a sum of positive squares in 2 ways, for example, as 96076441444 + 65778399729 = 309962^2 + 256473^2 .

It is a cyclic number.

It is not a de Polignac number, because 161854841173 - 2³³ = 153264906581 is a prime.

It is a super-2 number, since 2×161854841173² (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 (161854841177) 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, 1973839486 + ... + 1973839567.

It is an arithmetic number, because the mean of its divisors is an integer number (41450630067).

Almost surely, 2^161854841173 is an apocalyptic number.

It is an amenable number.

161854841173 is a deficient number, since it is larger than the sum of its proper divisors (3947679095).

161854841173 is an equidigital number, since it uses as much as digits as its factorization.

161854841173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3947679094.

The product of its digits is 645120, while the sum is 49.

The spelling of 161854841173 in words is "one hundred sixty-one billion, eight hundred fifty-four million, eight hundred forty-one thousand, one hundred seventy-three".