205215611705717 has 4 divisors (see below), whose sum is σ = 205215640605600. Its totient is φ = 205215582805836.

The previous prime is 205215611705677. The next prime is 205215611705719. The reversal of 205215611705717 is 717507116512502.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 205215611705717 - 2²² = 205215607511413 is a prime.

It is a super-2 number, since 2×205215611705717² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205215611705719) 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, 4384784 + ... + 20728182.

It is an arithmetic number, because the mean of its divisors is an integer number (51303910151400).

Almost surely, 2^{205215611705717} is an apocalyptic number.

It is an amenable number.

205215611705717 is a deficient number, since it is larger than the sum of its proper divisors (28899883).

205215611705717 is a wasteful number, since it uses less digits than its factorization.

205215611705717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28899882.

The product of its (nonzero) digits is 1029000, while the sum is 50.

The spelling of 205215611705717 in words is "two hundred five trillion, two hundred fifteen billion, six hundred eleven million, seven hundred five thousand, seven hundred seventeen".