684181728 has 120 divisors (see below), whose sum is σ = 2130658992. Its totient is φ = 214631424.

The previous prime is 684181727. The next prime is 684181739. The reversal of 684181728 is 827181486.

684181728 is a `hidden beast` number, since 68 + 418 + 172 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684181721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 36301 + ... + 51827.

Almost surely, 2^684181728 is an apocalyptic number.

684181728 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 684181728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1065329496).

684181728 is an abundant number, since it is smaller than the sum of its proper divisors (1446477264).

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

684181728 is a wasteful number, since it uses less digits than its factorization.

684181728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15566 (or 15549 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 684181728 is about 26156.8677023836. The cubic root of 684181728 is about 881.1648348662.

The spelling of 684181728 in words is "six hundred eighty-four million, one hundred eighty-one thousand, seven hundred twenty-eight".