206621213641 has 2 divisors, whose sum is σ = 206621213642. Its totient is φ = 206621213640.

The previous prime is 206621213639. The next prime is 206621213647. The reversal of 206621213641 is 146312126602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 189869347600 + 16751866041 = 435740^2 + 129429^2 .

It is a cyclic number.

It is not a de Polignac number, because 206621213641 - 2¹ = 206621213639 is a prime.

Together with 206621213639, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 206621213597 and 206621213606.

It is not a weakly prime, because it can be changed into another prime (206621213647) 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, 103310606820 + 103310606821.

It is an arithmetic number, because the mean of its divisors is an integer number (103310606821).

Almost surely, 2^206621213641 is an apocalyptic number.

It is an amenable number.

206621213641 is a deficient number, since it is larger than the sum of its proper divisors (1).

206621213641 is an equidigital number, since it uses as much as digits as its factorization.

206621213641 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 34.

The spelling of 206621213641 in words is "two hundred six billion, six hundred twenty-one million, two hundred thirteen thousand, six hundred forty-one".