205939661 has 2 divisors, whose sum is σ = 205939662. Its totient is φ = 205939660.

The previous prime is 205939637. The next prime is 205939691. The reversal of 205939661 is 166939502.

205939661 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., 205922500 + 17161 = 14350^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 205939661 - 2¹⁸ = 205677517 is a prime.

It is a super-2 number, since 2×205939661² = 84822287945589842, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205939691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102969830 + 102969831.

It is an arithmetic number, because the mean of its divisors is an integer number (102969831).

Almost surely, 2^205939661 is an apocalyptic number.

It is an amenable number.

205939661 is a deficient number, since it is larger than the sum of its proper divisors (1).

205939661 is an equidigital number, since it uses as much as digits as its factorization.

205939661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 87480, while the sum is 41.

The square root of 205939661 is about 14350.5979317936. The cubic root of 205939661 is about 590.5363895359.

The spelling of 205939661 in words is "two hundred five million, nine hundred thirty-nine thousand, six hundred sixty-one".