243042021 has 6 divisors (see below), whose sum is σ = 351060710. Its totient is φ = 162028008.

The previous prime is 243041983. The next prime is 243042089. The reversal of 243042021 is 120240342.

243042021 is a `hidden beast` number, since 243 + 0 + 420 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 239909121 + 3132900 = 15489^2 + 1770^2 .

It is a de Polignac number, because none of the positive numbers 2^k-243042021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 243041985 and 243042003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243052021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13502326 + ... + 13502343.

Almost surely, 2^243042021 is an apocalyptic number.

It is an amenable number.

243042021 is a deficient number, since it is larger than the sum of its proper divisors (108018689).

243042021 is a wasteful number, since it uses less digits than its factorization.

243042021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27004675 (or 27004672 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 243042021 is about 15589.8050340599. The cubic root of 243042021 is about 624.0611148845.

Adding to 243042021 its reverse (120240342), we get a palindrome (363282363).

The spelling of 243042021 in words is "two hundred forty-three million, forty-two thousand, twenty-one".