205105591 has 4 divisors (see below), whose sum is σ = 205355632. Its totient is φ = 204855552.

The previous prime is 205105531. The next prime is 205105619. The reversal of 205105591 is 195501502.

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

It is a cyclic number.

It is not a de Polignac number, because 205105591 - 2¹⁵ = 205072823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205105531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123786 + ... + 125431.

It is an arithmetic number, because the mean of its divisors is an integer number (51338908).

Almost surely, 2^205105591 is an apocalyptic number.

205105591 is a deficient number, since it is larger than the sum of its proper divisors (250041).

205105591 is an equidigital number, since it uses as much as digits as its factorization.

205105591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250040.

The product of its (nonzero) digits is 2250, while the sum is 28.

The square root of 205105591 is about 14321.5079862422. The cubic root of 205105591 is about 589.7380729539.

The spelling of 205105591 in words is "two hundred five million, one hundred five thousand, five hundred ninety-one".