205011661 has 2 divisors, whose sum is σ = 205011662. Its totient is φ = 205011660.

The previous prime is 205011637. The next prime is 205011689. The reversal of 205011661 is 166110502.

205011661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 148986436 + 56025225 = 12206^2 + 7485^2 .

It is a cyclic number.

It is not a de Polignac number, because 205011661 - 2⁵ = 205011629 is a prime.

It is a super-2 number, since 2×205011661² = 84059562291957842, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205011601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102505830 + 102505831.

It is an arithmetic number, because the mean of its divisors is an integer number (102505831).

Almost surely, 2^205011661 is an apocalyptic number.

It is an amenable number.

205011661 is a deficient number, since it is larger than the sum of its proper divisors (1).

205011661 is an equidigital number, since it uses as much as digits as its factorization.

205011661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 205011661 is about 14318.2282772695. The cubic root of 205011661 is about 589.6480338751.

The spelling of 205011661 in words is "two hundred five million, eleven thousand, six hundred sixty-one".