205105621605 has 16 divisors (see below), whose sum is σ = 347473053504. Its totient is φ = 102954978560.

The previous prime is 205105621603. The next prime is 205105621613. The reversal of 205105621605 is 506126501502.

It is not a de Polignac number, because 205105621605 - 2¹ = 205105621603 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205105621603) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 402167631 + ... + 402168140.

It is an arithmetic number, because the mean of its divisors is an integer number (21717065844).

Almost surely, 2^205105621605 is an apocalyptic number.

It is an amenable number.

205105621605 is a deficient number, since it is larger than the sum of its proper divisors (142367431899).

205105621605 is a wasteful number, since it uses less digits than its factorization.

205105621605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804335796.

The product of its (nonzero) digits is 18000, while the sum is 33.

The spelling of 205105621605 in words is "two hundred five billion, one hundred five million, six hundred twenty-one thousand, six hundred five".