161188391 has 32 divisors (see below), whose sum is σ = 208118400. Its totient is φ = 123959808.

The previous prime is 161188369. The next prime is 161188403. The reversal of 161188391 is 193881161.

161188391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161188391 - 2⁶ = 161188327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161188091) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 164495 + ... + 165471.

It is an arithmetic number, because the mean of its divisors is an integer number (6503700).

Almost surely, 2^161188391 is an apocalyptic number.

161188391 is a deficient number, since it is larger than the sum of its proper divisors (46930009).

161188391 is an equidigital number, since it uses as much as digits as its factorization.

161188391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1048 (or 1034 counting only the distinct ones).

The product of its digits is 10368, while the sum is 38.

The square root of 161188391 is about 12695.9990154379. Note that the first 3 decimals coincide. The cubic root of 161188391 is about 544.2242882364.

The spelling of 161188391 in words is "one hundred sixty-one million, one hundred eighty-eight thousand, three hundred ninety-one".