160991 has 4 divisors (see below), whose sum is σ = 162000. Its totient is φ = 159984.

The previous prime is 160981. The next prime is 160997. The reversal of 160991 is 199061.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 199061 = 137 ⋅1453.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-160991 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 160991.

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 160991.

It is not an unprimeable number, because it can be changed into a prime (160997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 206 + ... + 603.

It is an arithmetic number, because the mean of its divisors is an integer number (40500).

2¹⁶⁰⁹⁹¹ is an apocalyptic number.

160991 is a deficient number, since it is larger than the sum of its proper divisors (1009).

160991 is an equidigital number, since it uses as much as digits as its factorization.

160991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1008.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 160991 is about 401.2368377904. The cubic root of 160991 is about 54.4002045480.

The spelling of 160991 in words is "one hundred sixty thousand, nine hundred ninety-one".