243661 has 8 divisors (see below), whose sum is σ = 281664. Its totient is φ = 208320.

The previous prime is 243647. The next prime is 243671. The reversal of 243661 is 166342.

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 243661 - 2⁷ = 243533 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243631) 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, 465 + ... + 838.

It is an arithmetic number, because the mean of its divisors is an integer number (35208).

2²⁴³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

243661 is a deficient number, since it is larger than the sum of its proper divisors (38003).

243661 is a wasteful number, since it uses less digits than its factorization.

243661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331.

The product of its digits is 864, while the sum is 22.

The square root of 243661 is about 493.6202994205. The cubic root of 243661 is about 62.4590451691.

The spelling of 243661 in words is "two hundred forty-three thousand, six hundred sixty-one".