243206021 has 2 divisors, whose sum is σ = 243206022. Its totient is φ = 243206020.

The previous prime is 243206011. The next prime is 243206053. The reversal of 243206021 is 120602342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 236728996 + 6477025 = 15386^2 + 2545^2 .

It is a cyclic number.

It is not a de Polignac number, because 243206021 - 2⁶ = 243205957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 243205984 and 243206002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243206011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121603010 + 121603011.

It is an arithmetic number, because the mean of its divisors is an integer number (121603011).

Almost surely, 2^243206021 is an apocalyptic number.

It is an amenable number.

243206021 is a deficient number, since it is larger than the sum of its proper divisors (1).

243206021 is an equidigital number, since it uses as much as digits as its factorization.

243206021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 243206021 is about 15595.0639947388. The cubic root of 243206021 is about 624.2014514001.

Adding to 243206021 its reverse (120602342), we get a palindrome (363808363).

The spelling of 243206021 in words is "two hundred forty-three million, two hundred six thousand, twenty-one".