991209208559 has 2 divisors, whose sum is σ = 991209208560. Its totient is φ = 991209208558.

The previous prime is 991209208537. The next prime is 991209208589. The reversal of 991209208559 is 955802902199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991209208559 - 2²⁰ = 991208159983 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991209208498 and 991209208507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991209208589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495604604279 + 495604604280.

It is an arithmetic number, because the mean of its divisors is an integer number (495604604280).

Almost surely, 2^991209208559 is an apocalyptic number.

991209208559 is a deficient number, since it is larger than the sum of its proper divisors (1).

991209208559 is an equidigital number, since it uses as much as digits as its factorization.

991209208559 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5248800, while the sum is 59.

The spelling of 991209208559 in words is "nine hundred ninety-one billion, two hundred nine million, two hundred eight thousand, five hundred fifty-nine".