205687131361 has 4 divisors (see below), whose sum is σ = 206162159812. Its totient is φ = 205212102912.

The previous prime is 205687131359. The next prime is 205687131389. The reversal of 205687131361 is 163131786502.

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 54244739025 + 151442392336 = 232905^2 + 389156^2 .

It is a cyclic number.

It is not a de Polignac number, because 205687131361 - 2¹ = 205687131359 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205687131061) 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, 237513576 + ... + 237514441.

It is an arithmetic number, because the mean of its divisors is an integer number (51540539953).

Almost surely, 2^205687131361 is an apocalyptic number.

It is an amenable number.

205687131361 is a deficient number, since it is larger than the sum of its proper divisors (475028451).

205687131361 is an equidigital number, since it uses as much as digits as its factorization.

205687131361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475028450.

The product of its (nonzero) digits is 181440, while the sum is 43.

The spelling of 205687131361 in words is "two hundred five billion, six hundred eighty-seven million, one hundred thirty-one thousand, three hundred sixty-one".