999999818878689 has 48 divisors (see below), whose sum is σ = 1469694532101120. Its totient is φ = 655036108865280.

The previous prime is 999999818878663. The next prime is 999999818878789. The reversal of 999999818878689 is 986878818999999.

It is a happy number.

999999818878689 is a `hidden beast` number, since 9 + 99 + 99 + 98 + 188 + 78 + 6 + 89 = 666.

It is not a de Polignac number, because 999999818878689 - 2¹⁵ = 999999818845921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (999999818878789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4091881702 + ... + 4092126080.

It is an arithmetic number, because the mean of its divisors is an integer number (30618636085440).

Almost surely, 2^{999999818878689} is an apocalyptic number.

It is an amenable number.

999999818878689 is a deficient number, since it is larger than the sum of its proper divisors (469694713222431).

999999818878689 is a wasteful number, since it uses less digits than its factorization.

999999818878689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252390 (or 252387 counting only the distinct ones).

The product of its digits is 6582589784064, while the sum is 117.

The spelling of 999999818878689 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, eight hundred eighteen million, eight hundred seventy-eight thousand, six hundred eighty-nine".