205606561 has 2 divisors, whose sum is σ = 205606562. Its totient is φ = 205606560.

The previous prime is 205606537. The next prime is 205606571. The reversal of 205606561 is 165606502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 191656336 + 13950225 = 13844^2 + 3735^2 .

It is a cyclic number.

It is not a de Polignac number, because 205606561 - 2¹⁷ = 205475489 is a prime.

It is not a weakly prime, because it can be changed into another prime (205606501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102803280 + 102803281.

It is an arithmetic number, because the mean of its divisors is an integer number (102803281).

Almost surely, 2^205606561 is an apocalyptic number.

It is an amenable number.

205606561 is a deficient number, since it is larger than the sum of its proper divisors (1).

205606561 is an equidigital number, since it uses as much as digits as its factorization.

205606561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 205606561 is about 14338.9874468179. The cubic root of 205606561 is about 590.2178272579.

The spelling of 205606561 in words is "two hundred five million, six hundred six thousand, five hundred sixty-one".