243240321 has 4 divisors (see below), whose sum is σ = 324320432. Its totient is φ = 162160212.

The previous prime is 243240317. The next prime is 243240323. The reversal of 243240321 is 123042342.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 243240321 - 2² = 243240317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (243240323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40540051 + ... + 40540056.

It is an arithmetic number, because the mean of its divisors is an integer number (81080108).

Almost surely, 2^243240321 is an apocalyptic number.

It is an amenable number.

243240321 is a deficient number, since it is larger than the sum of its proper divisors (81080111).

243240321 is an equidigital number, since it uses as much as digits as its factorization.

243240321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81080110.

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 243240321 is about 15596.1636629012. The cubic root of 243240321 is about 624.2307942912.

Adding to 243240321 its reverse (123042342), we get a palindrome (366282663).

The spelling of 243240321 in words is "two hundred forty-three million, two hundred forty thousand, three hundred twenty-one".