681684 has 12 divisors (see below), whose sum is σ = 1590624. Its totient is φ = 227224.

The previous prime is 681677. The next prime is 681689. The reversal of 681684 is 486186.

681684 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28392 + ... + 28415.

It is an arithmetic number, because the mean of its divisors is an integer number (132552).

2⁶⁸¹⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

681684 is an abundant number, since it is smaller than the sum of its proper divisors (908940).

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

681684 is a wasteful number, since it uses less digits than its factorization.

681684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56814 (or 56812 counting only the distinct ones).

The product of its digits is 9216, while the sum is 33.

The square root of 681684 is about 825.6415687210. The cubic root of 681684 is about 88.0091243982.

Adding to 681684 its product of digits (9216), we get a triangular number (690900 = T₁₁₇₅).

The spelling of 681684 in words is "six hundred eighty-one thousand, six hundred eighty-four".