205087681 has 4 divisors (see below), whose sum is σ = 212159700. Its totient is φ = 198015664.

The previous prime is 205087667. The next prime is 205087693. The reversal of 205087681 is 186780502.

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

It can be written as a sum of positive squares in 2 ways, for example, as 105267600 + 99820081 = 10260^2 + 9991^2 .

It is a cyclic number.

It is not a de Polignac number, because 205087681 - 2²³ = 196699073 is a prime.

It is a super-2 number, since 2×205087681² = 84121913795915522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 205087681.

It is not an unprimeable number, because it can be changed into a prime (205087621) 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 3 ways as a sum of consecutive naturals, for example, 3535966 + ... + 3536023.

It is an arithmetic number, because the mean of its divisors is an integer number (53039925).

Almost surely, 2^205087681 is an apocalyptic number.

It is an amenable number.

205087681 is a deficient number, since it is larger than the sum of its proper divisors (7072019).

205087681 is an equidigital number, since it uses as much as digits as its factorization.

205087681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7072018.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 205087681 is about 14320.8826892758. The cubic root of 205087681 is about 589.7209069724.

The spelling of 205087681 in words is "two hundred five million, eighty-seven thousand, six hundred eighty-one".