243681 has 8 divisors (see below), whose sum is σ = 332640. Its totient is φ = 158592.

The previous prime is 243673. The next prime is 243701. The reversal of 243681 is 186342.

It is a happy number.

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

It is not a de Polignac number, because 243681 - 2³ = 243673 is a prime.

It is a super-2 number, since 2×243681² = 118760859522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (243631) 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, 816 + ... + 1073.

It is an arithmetic number, because the mean of its divisors is an integer number (41580).

2²⁴³⁶⁸¹ is an apocalyptic number.

It is an amenable number.

243681 is a deficient number, since it is larger than the sum of its proper divisors (88959).

243681 is a wasteful number, since it uses less digits than its factorization.

243681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1935.

The product of its digits is 1152, while the sum is 24.

The square root of 243681 is about 493.6405574910. The cubic root of 243681 is about 62.4607540279.

The spelling of 243681 in words is "two hundred forty-three thousand, six hundred eighty-one".