161861870391 has 8 divisors (see below), whose sum is σ = 232417044720. Its totient is φ = 99607304832.

The previous prime is 161861870383. The next prime is 161861870399. The reversal of 161861870391 is 193078168161.

It is an interprime number because it is at equal distance from previous prime (161861870383) and next prime (161861870399).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161861870391 - 2³ = 161861870383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161861870399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2075152146 + ... + 2075152223.

It is an arithmetic number, because the mean of its divisors is an integer number (29052130590).

Almost surely, 2^161861870391 is an apocalyptic number.

161861870391 is a deficient number, since it is larger than the sum of its proper divisors (70555174329).

161861870391 is a wasteful number, since it uses less digits than its factorization.

161861870391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4150304385.

The product of its (nonzero) digits is 435456, while the sum is 51.

The spelling of 161861870391 in words is "one hundred sixty-one billion, eight hundred sixty-one million, eight hundred seventy thousand, three hundred ninety-one".