206611821649 has 2 divisors, whose sum is σ = 206611821650. Its totient is φ = 206611821648.

The previous prime is 206611821631. The next prime is 206611821739. The reversal of 206611821649 is 946128116602.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 196964653249 + 9647168400 = 443807^2 + 98220^2 .

It is a cyclic number.

It is not a de Polignac number, because 206611821649 - 2⁹ = 206611821137 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 206611821599 and 206611821608.

It is not a weakly prime, because it can be changed into another prime (206611821349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103305910824 + 103305910825.

It is an arithmetic number, because the mean of its divisors is an integer number (103305910825).

Almost surely, 2^206611821649 is an apocalyptic number.

It is an amenable number.

206611821649 is a deficient number, since it is larger than the sum of its proper divisors (1).

206611821649 is an equidigital number, since it uses as much as digits as its factorization.

206611821649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 248832, while the sum is 46.

The spelling of 206611821649 in words is "two hundred six billion, six hundred eleven million, eight hundred twenty-one thousand, six hundred forty-nine".