205455661 has 2 divisors, whose sum is σ = 205455662. Its totient is φ = 205455660.

The previous prime is 205455643. The next prime is 205455671. The reversal of 205455661 is 166554502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 105575625 + 99880036 = 10275^2 + 9994^2 .

It is a cyclic number.

It is not a de Polignac number, because 205455661 - 2⁷ = 205455533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205455671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102727830 + 102727831.

It is an arithmetic number, because the mean of its divisors is an integer number (102727831).

Almost surely, 2^205455661 is an apocalyptic number.

It is an amenable number.

205455661 is a deficient number, since it is larger than the sum of its proper divisors (1).

205455661 is an equidigital number, since it uses as much as digits as its factorization.

205455661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36000, while the sum is 34.

The square root of 205455661 is about 14333.7246031867. The cubic root of 205455661 is about 590.0733998503.

It can be divided in two parts, 205455 and 661, that added together give a square (206116 = 454²).

The spelling of 205455661 in words is "two hundred five million, four hundred fifty-five thousand, six hundred sixty-one".