999999818878663 has 2 divisors, whose sum is σ = 999999818878664. Its totient is φ = 999999818878662.

The previous prime is 999999818878631. The next prime is 999999818878789. The reversal of 999999818878663 is 366878818999999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 999999818878663 - 2⁵ = 999999818878631 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 999999818878663.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199999818878663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999909439331 + 499999909439332.

It is an arithmetic number, because the mean of its divisors is an integer number (499999909439332).

Almost surely, 2^{999999818878663} is an apocalyptic number.

999999818878663 is a deficient number, since it is larger than the sum of its proper divisors (1).

999999818878663 is an equidigital number, since it uses as much as digits as its factorization.

999999818878663 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1645647446016, while the sum is 109.

The spelling of 999999818878663 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, eight hundred eighteen million, eight hundred seventy-eight thousand, six hundred sixty-three".