243404221 has 4 divisors (see below), whose sum is σ = 251797500. Its totient is φ = 235010944.

The previous prime is 243404207. The next prime is 243404251. The reversal of 243404221 is 122404342.

It is a happy number.

243404221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 39200121 + 204204100 = 6261^2 + 14290^2 .

It is a cyclic number.

It is not a de Polignac number, because 243404221 - 2⁹ = 243403709 is a prime.

It is a super-2 number, since 2×243404221² = 118491229601233682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 243404192 and 243404201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243404251) 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, 4196596 + ... + 4196653.

It is an arithmetic number, because the mean of its divisors is an integer number (62949375).

Almost surely, 2^243404221 is an apocalyptic number.

It is an amenable number.

243404221 is a deficient number, since it is larger than the sum of its proper divisors (8393279).

243404221 is an equidigital number, since it uses as much as digits as its factorization.

243404221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8393278.

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 243404221 is about 15601.4172753632. The cubic root of 243404221 is about 624.3709690445.

Adding to 243404221 its reverse (122404342), we get a palindrome (365808563).

It can be divided in two parts, 24340 and 4221, that added together give a 4-th power (28561 = 13⁴).

The spelling of 243404221 in words is "two hundred forty-three million, four hundred four thousand, two hundred twenty-one".