243403021 has 4 divisors (see below), whose sum is σ = 243704700. Its totient is φ = 243101344.

The previous prime is 243403007. The next prime is 243403033. The reversal of 243403021 is 120304342.

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 223502500 + 19900521 = 14950^2 + 4461^2 .

It is a cyclic number.

It is not a de Polignac number, because 243403021 - 2¹⁹ = 242878733 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 243403021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243403421) 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, 149626 + ... + 151243.

It is an arithmetic number, because the mean of its divisors is an integer number (60926175).

Almost surely, 2^243403021 is an apocalyptic number.

It is an amenable number.

243403021 is a deficient number, since it is larger than the sum of its proper divisors (301679).

243403021 is an equidigital number, since it uses as much as digits as its factorization.

243403021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301678.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 243403021 is about 15601.3788172712. The cubic root of 243403021 is about 624.3699429785.

Adding to 243403021 its reverse (120304342), we get a palindrome (363707363).

The spelling of 243403021 in words is "two hundred forty-three million, four hundred three thousand, twenty-one".