206631661 has 2 divisors, whose sum is σ = 206631662. Its totient is φ = 206631660.

The previous prime is 206631653. The next prime is 206631673. The reversal of 206631661 is 166136602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 154878025 + 51753636 = 12445^2 + 7194^2 .

It is a cyclic number.

It is not a de Polignac number, because 206631661 - 2³ = 206631653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206631361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103315830 + 103315831.

It is an arithmetic number, because the mean of its divisors is an integer number (103315831).

Almost surely, 2^206631661 is an apocalyptic number.

It is an amenable number.

206631661 is a deficient number, since it is larger than the sum of its proper divisors (1).

206631661 is an equidigital number, since it uses as much as digits as its factorization.

206631661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 206631661 is about 14374.6882053142. The cubic root of 206631661 is about 591.1970916635.

The spelling of 206631661 in words is "two hundred six million, six hundred thirty-one thousand, six hundred sixty-one".