999999818878690 has 128 divisors (see below), whose sum is σ = 2184289592463360. Its totient is φ = 321780558962688.

The previous prime is 999999818878663. The next prime is 999999818878789. The reversal of 999999818878690 is 96878818999999.

999999818878690 is a nontrivial binomial coefficient, being equal to C(44721356, 2).

It is a super-2 number, since 2×999999818878690² (a number of 31 digits) contains 22 as substring.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 781984854 + ... + 783262606.

It is an arithmetic number, because the mean of its divisors is an integer number (17064762441120).

Almost surely, 2^{999999818878690} is an apocalyptic number.

999999818878690 is the 44721355-th triangular number and also the 22360678-th hexagonal number.

999999818878690 is the 14907119-th centered nonagonal number.

999999818878690 is an abundant number, since it is smaller than the sum of its proper divisors (1184289773584670).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

999999818878690 is a wasteful number, since it uses less digits than its factorization.

999999818878690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1279636.

The product of its (nonzero) digits is 822823723008, while the sum is 109.

The spelling of 999999818878690 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, eight hundred eighteen million, eight hundred seventy-eight thousand, six hundred ninety".