206643950521 has 2 divisors, whose sum is σ = 206643950522. Its totient is φ = 206643950520.

The previous prime is 206643950479. The next prime is 206643950531. The reversal of 206643950521 is 125059346602.

206643950521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 122825015296 + 83818935225 = 350464^2 + 289515^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206643950521 is a prime.

It is not a weakly prime, because it can be changed into another prime (206643950531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103321975260 + 103321975261.

It is an arithmetic number, because the mean of its divisors is an integer number (103321975261).

Almost surely, 2^206643950521 is an apocalyptic number.

It is an amenable number.

206643950521 is a deficient number, since it is larger than the sum of its proper divisors (1).

206643950521 is an equidigital number, since it uses as much as digits as its factorization.

206643950521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 388800, while the sum is 43.

The spelling of 206643950521 in words is "two hundred six billion, six hundred forty-three million, nine hundred fifty thousand, five hundred twenty-one".