161391 has 8 divisors (see below), whose sum is σ = 224640. Its totient is φ = 102872.

The previous prime is 161387. The next prime is 161407. The reversal of 161391 is 193161.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 161391 - 2² = 161387 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 161391.

It is not an unprimeable number, because it can be changed into a prime (161341) 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, 1101 + ... + 1238.

It is an arithmetic number, because the mean of its divisors is an integer number (28080).

2¹⁶¹³⁹¹ is an apocalyptic number.

161391 is a deficient number, since it is larger than the sum of its proper divisors (63249).

161391 is a wasteful number, since it uses less digits than its factorization.

161391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2365.

The product of its digits is 162, while the sum is 21.

The square root of 161391 is about 401.7349872739. The cubic root of 161391 is about 54.4452217329.

The spelling of 161391 in words is "one hundred sixty-one thousand, three hundred ninety-one".