161327591 has 4 divisors (see below), whose sum is σ = 163537632. Its totient is φ = 159117552.

The previous prime is 161327581. The next prime is 161327599. The reversal of 161327591 is 195723161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195723161 = 19 ⋅10301219.

It is a cyclic number.

It is not a de Polignac number, because 161327591 - 2¹⁴ = 161311207 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161327599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1104911 + ... + 1105056.

It is an arithmetic number, because the mean of its divisors is an integer number (40884408).

Almost surely, 2^161327591 is an apocalyptic number.

161327591 is a deficient number, since it is larger than the sum of its proper divisors (2210041).

161327591 is an equidigital number, since it uses as much as digits as its factorization.

161327591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2210040.

The product of its digits is 11340, while the sum is 35.

The square root of 161327591 is about 12701.4798744083. The cubic root of 161327591 is about 544.3809046107.

The spelling of 161327591 in words is "one hundred sixty-one million, three hundred twenty-seven thousand, five hundred ninety-one".