205553661 has 4 divisors (see below), whose sum is σ = 274071552. Its totient is φ = 137035772.

The previous prime is 205553657. The next prime is 205553669. The reversal of 205553661 is 166355502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 205553661 - 2² = 205553657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205553669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34258941 + ... + 34258946.

It is an arithmetic number, because the mean of its divisors is an integer number (68517888).

Almost surely, 2^205553661 is an apocalyptic number.

It is an amenable number.

205553661 is a deficient number, since it is larger than the sum of its proper divisors (68517891).

205553661 is an equidigital number, since it uses as much as digits as its factorization.

205553661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68517890.

The product of its (nonzero) digits is 27000, while the sum is 33.

The square root of 205553661 is about 14337.1427069692. The cubic root of 205553661 is about 590.1672043579.

The spelling of 205553661 in words is "two hundred five million, five hundred fifty-three thousand, six hundred sixty-one".