243664 has 20 divisors (see below), whose sum is σ = 480004. Its totient is φ = 119808.

The previous prime is 243647. The next prime is 243671. The reversal of 243664 is 466342.

It can be written as a sum of positive squares in 2 ways, for example, as 90000 + 153664 = 300^2 + 392^2 .

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1474 + ... + 1630.

2²⁴³⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

243664 is a deficient number, since it is larger than the sum of its proper divisors (236340).

243664 is a wasteful number, since it uses less digits than its factorization.

243664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 256 counting only the distinct ones).

The product of its digits is 3456, while the sum is 25.

The square root of 243664 is about 493.6233381841. The cubic root of 243664 is about 62.4593015039.

It can be divided in two parts, 2436 and 64, that added together give a square (2500 = 50²).

The spelling of 243664 in words is "two hundred forty-three thousand, six hundred sixty-four".