205312517 has 2 divisors, whose sum is σ = 205312518. Its totient is φ = 205312516.

The previous prime is 205312493. The next prime is 205312571. The reversal of 205312517 is 715213502.

Together with next prime (205312571) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 200533921 + 4778596 = 14161^2 + 2186^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205312517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205312117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102656258 + 102656259.

It is an arithmetic number, because the mean of its divisors is an integer number (102656259).

Almost surely, 2^205312517 is an apocalyptic number.

It is an amenable number.

205312517 is a deficient number, since it is larger than the sum of its proper divisors (1).

205312517 is an equidigital number, since it uses as much as digits as its factorization.

205312517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 205312517 is about 14328.7304741209. The cubic root of 205312517 is about 589.9363303888.

The spelling of 205312517 in words is "two hundred five million, three hundred twelve thousand, five hundred seventeen".