206406838021 has 2 divisors, whose sum is σ = 206406838022. Its totient is φ = 206406838020.

The previous prime is 206406838009. The next prime is 206406838049. The reversal of 206406838021 is 120838604602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 198973984225 + 7432853796 = 446065^2 + 86214^2 .

It is a cyclic number.

It is not a de Polignac number, because 206406838021 - 2⁷ = 206406837893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206406838081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103203419010 + 103203419011.

It is an arithmetic number, because the mean of its divisors is an integer number (103203419011).

Almost surely, 2^206406838021 is an apocalyptic number.

It is an amenable number.

206406838021 is a deficient number, since it is larger than the sum of its proper divisors (1).

206406838021 is an equidigital number, since it uses as much as digits as its factorization.

206406838021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 110592, while the sum is 40.

The spelling of 206406838021 in words is "two hundred six billion, four hundred six million, eight hundred thirty-eight thousand, twenty-one".