161957391 has 8 divisors (see below), whose sum is σ = 216002304. Its totient is φ = 107942040.

The previous prime is 161957381. The next prime is 161957407. The reversal of 161957391 is 193759161.

161957391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 161957391 - 2⁵ = 161957359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161957321) 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, 15736 + ... + 23906.

It is an arithmetic number, because the mean of its divisors is an integer number (27000288).

Almost surely, 2^161957391 is an apocalyptic number.

161957391 is a deficient number, since it is larger than the sum of its proper divisors (54044913).

161957391 is an equidigital number, since it uses as much as digits as its factorization.

161957391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14781.

The product of its digits is 51030, while the sum is 42.

The square root of 161957391 is about 12726.2481116785. The cubic root of 161957391 is about 545.0883800222.

The spelling of 161957391 in words is "one hundred sixty-one million, nine hundred fifty-seven thousand, three hundred ninety-one".