161491 has 8 divisors (see below), whose sum is σ = 180144. Its totient is φ = 143520.

The previous prime is 161471. The next prime is 161503. The reversal of 161491 is 194161.

161491 = T₁₁₀ + T₁₁₁ + ... + T₁₃₁.

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 161491 - 2⁵ = 161459 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 445 + ... + 721.

It is an arithmetic number, because the mean of its divisors is an integer number (22518).

2¹⁶¹⁴⁹¹ is an apocalyptic number.

161491 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161491 is a deficient number, since it is larger than the sum of its proper divisors (18653).

161491 is a wasteful number, since it uses less digits than its factorization.

161491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341.

The product of its digits is 216, while the sum is 22.

The square root of 161491 is about 401.8594281587. The cubic root of 161491 is about 54.4564644046.

The spelling of 161491 in words is "one hundred sixty-one thousand, four hundred ninety-one".