205213871653717 has 4 divisors (see below), whose sum is σ = 205217112055456. Its totient is φ = 205210631251980.

The previous prime is 205213871653643. The next prime is 205213871653733. The reversal of 205213871653717 is 717356178312502.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-205213871653717 is a prime.

It is a super-2 number, since 2×205213871653717² (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 (205213871653517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1620105873 + ... + 1620232534.

It is an arithmetic number, because the mean of its divisors is an integer number (51304278013864).

Almost surely, 2^{205213871653717} is an apocalyptic number.

It is an amenable number.

205213871653717 is a deficient number, since it is larger than the sum of its proper divisors (3240401739).

205213871653717 is an equidigital number, since it uses as much as digits as its factorization.

205213871653717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3240401738.

The product of its (nonzero) digits is 14817600, while the sum is 58.

The spelling of 205213871653717 in words is "two hundred five trillion, two hundred thirteen billion, eight hundred seventy-one million, six hundred fifty-three thousand, seven hundred seventeen".