205011681 has 16 divisors (see below), whose sum is σ = 312645504. Its totient is φ = 117057024.

The previous prime is 205011661. The next prime is 205011689. The reversal of 205011681 is 186110502.

It is not a de Polignac number, because 205011681 - 2⁷ = 205011553 is a prime.

It is a super-2 number, since 2×205011681² = 84059578692891522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (205011689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30481 + ... + 36593.

It is an arithmetic number, because the mean of its divisors is an integer number (19540344).

Almost surely, 2^205011681 is an apocalyptic number.

205011681 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

205011681 is a deficient number, since it is larger than the sum of its proper divisors (107633823).

205011681 is a wasteful number, since it uses less digits than its factorization.

205011681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7720.

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 205011681 is about 14318.2289756799. The cubic root of 205011681 is about 589.6480530495.

It can be divided in two parts, 2050 and 11681, that added together give a palindrome (13731).

The spelling of 205011681 in words is "two hundred five million, eleven thousand, six hundred eighty-one".