999998387795857 has 2 divisors, whose sum is σ = 999998387795858. Its totient is φ = 999998387795856.

The previous prime is 999998387795819. The next prime is 999998387795879. The reversal of 999998387795857 is 758597783899999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 561039907610961 + 438958480184896 = 23686281^2 + 20951336^2 .

It is an emirp because it is prime and its reverse (758597783899999) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999998387795857 is a prime.

It is not a weakly prime, because it can be changed into another prime (999998387795887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999193897928 + 499999193897929.

It is an arithmetic number, because the mean of its divisors is an integer number (499999193897929).

Almost surely, 2^{999998387795857} is an apocalyptic number.

It is an amenable number.

999998387795857 is a deficient number, since it is larger than the sum of its proper divisors (1).

999998387795857 is an equidigital number, since it uses as much as digits as its factorization.

999998387795857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6999715699200, while the sum is 112.

The spelling of 999998387795857 in words is "nine hundred ninety-nine trillion, nine hundred ninety-eight billion, three hundred eighty-seven million, seven hundred ninety-five thousand, eight hundred fifty-seven".