684404021808 has 120 divisors (see below), whose sum is σ = 2139114785808. Its totient is φ = 210585837312.

The previous prime is 684404021803. The next prime is 684404021809. The reversal of 684404021808 is 808120404486.

684404021808 is a `hidden beast` number, since 68 + 4 + 4 + 0 + 402 + 180 + 8 = 666.

It is a super-3 number, since 3×684404021808³ (a number of 36 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (684404021803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6719835 + ... + 6820922.

Almost surely, 2^684404021808 is an apocalyptic number.

It is an amenable number.

684404021808 is an abundant number, since it is smaller than the sum of its proper divisors (1454710764000).

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

684404021808 is a wasteful number, since it uses less digits than its factorization.

684404021808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13540793 (or 13540775 counting only the distinct ones).

The product of its (nonzero) digits is 393216, while the sum is 45.

The spelling of 684404021808 in words is "six hundred eighty-four billion, four hundred four million, twenty-one thousand, eight hundred eight".