161684581 has 8 divisors (see below), whose sum is σ = 165090240. Its totient is φ = 158313792.

The previous prime is 161684573. The next prime is 161684591. The reversal of 161684581 is 185486161.

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 161684581 - 2³ = 161684573 is a prime.

It is a super-2 number, since 2×161684581² = 52283807466291122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161684521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 760 + ... + 17998.

It is an arithmetic number, because the mean of its divisors is an integer number (20636280).

Almost surely, 2^161684581 is an apocalyptic number.

It is an amenable number.

161684581 is a deficient number, since it is larger than the sum of its proper divisors (3405659).

161684581 is a wasteful number, since it uses less digits than its factorization.

161684581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17435.

The product of its digits is 46080, while the sum is 40.

The square root of 161684581 is about 12715.5251956024. The cubic root of 161684581 is about 544.7821489939.

The spelling of 161684581 in words is "one hundred sixty-one million, six hundred eighty-four thousand, five hundred eighty-one".