206620656661 has 2 divisors, whose sum is σ = 206620656662. Its totient is φ = 206620656660.

The previous prime is 206620656637. The next prime is 206620656673. The reversal of 206620656661 is 166656026602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204931857636 + 1688799025 = 452694^2 + 41095^2 .

It is a cyclic number.

It is not a de Polignac number, because 206620656661 - 2⁷ = 206620656533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206620656631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103310328330 + 103310328331.

It is an arithmetic number, because the mean of its divisors is an integer number (103310328331).

Almost surely, 2^206620656661 is an apocalyptic number.

It is an amenable number.

206620656661 is a deficient number, since it is larger than the sum of its proper divisors (1).

206620656661 is an equidigital number, since it uses as much as digits as its factorization.

206620656661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 933120, while the sum is 46.

The spelling of 206620656661 in words is "two hundred six billion, six hundred twenty million, six hundred fifty-six thousand, six hundred sixty-one".