205687131317 has 2 divisors, whose sum is σ = 205687131318. Its totient is φ = 205687131316.

The previous prime is 205687131313. The next prime is 205687131359. The reversal of 205687131317 is 713131786502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 205667692036 + 19439281 = 453506^2 + 4409^2 .

It is a cyclic number.

It is not a de Polignac number, because 205687131317 - 2² = 205687131313 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205687131313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102843565658 + 102843565659.

It is an arithmetic number, because the mean of its divisors is an integer number (102843565659).

Almost surely, 2^205687131317 is an apocalyptic number.

It is an amenable number.

205687131317 is a deficient number, since it is larger than the sum of its proper divisors (1).

205687131317 is an equidigital number, since it uses as much as digits as its factorization.

205687131317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 211680, while the sum is 44.

The spelling of 205687131317 in words is "two hundred five billion, six hundred eighty-seven million, one hundred thirty-one thousand, three hundred seventeen".