205715987 has 2 divisors, whose sum is σ = 205715988. Its totient is φ = 205715986.

The previous prime is 205715947. The next prime is 205716013. The reversal of 205715987 is 789517502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 205715987 - 2¹⁶ = 205650451 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (205715947) 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 as a sum of consecutive naturals, namely, 102857993 + 102857994.

It is an arithmetic number, because the mean of its divisors is an integer number (102857994).

Almost surely, 2^205715987 is an apocalyptic number.

205715987 is a deficient number, since it is larger than the sum of its proper divisors (1).

205715987 is an equidigital number, since it uses as much as digits as its factorization.

205715987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 176400, while the sum is 44.

The square root of 205715987 is about 14342.8026201297. The cubic root of 205715987 is about 590.3225154245.

The spelling of 205715987 in words is "two hundred five million, seven hundred fifteen thousand, nine hundred eighty-seven".