163581 has 8 divisors (see below), whose sum is σ = 237984. Its totient is φ = 99120.

The previous prime is 163573. The next prime is 163601. The reversal of 163581 is 185361.

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

It is not a de Polignac number, because 163581 - 2³ = 163573 is a prime.

It is a super-2 number, since 2×163581² = 53517487122, which contains 22 as substring.

It is a Curzon number.

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 163581.

It is not an unprimeable number, because it can be changed into a prime (163561) 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, 2446 + ... + 2511.

It is an arithmetic number, because the mean of its divisors is an integer number (29748).

2¹⁶³⁵⁸¹ is an apocalyptic number.

163581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

163581 is a deficient number, since it is larger than the sum of its proper divisors (74403).

163581 is a wasteful number, since it uses less digits than its factorization.

163581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4971.

The product of its digits is 720, while the sum is 24.

The square root of 163581 is about 404.4514804028. The cubic root of 163581 is about 54.6903815080.

The spelling of 163581 in words is "one hundred sixty-three thousand, five hundred eighty-one".