205610561 has 4 divisors (see below), whose sum is σ = 221426772. Its totient is φ = 189794352.

The previous prime is 205610549. The next prime is 205610599. The reversal of 205610561 is 165016502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 34000561 + 171610000 = 5831^2 + 13100^2 .

It is a cyclic number.

It is not a de Polignac number, because 205610561 - 2¹⁸ = 205348417 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 205610561.

It is not an unprimeable number, because it can be changed into a prime (205210561) 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 in 3 ways as a sum of consecutive naturals, for example, 7908086 + ... + 7908111.

It is an arithmetic number, because the mean of its divisors is an integer number (55356693).

Almost surely, 2^205610561 is an apocalyptic number.

It is an amenable number.

205610561 is a deficient number, since it is larger than the sum of its proper divisors (15816211).

205610561 is a wasteful number, since it uses less digits than its factorization.

205610561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15816210.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 205610561 is about 14339.1269260022. The cubic root of 205610561 is about 590.2216547233.

The spelling of 205610561 in words is "two hundred five million, six hundred ten thousand, five hundred sixty-one".