684400 has 60 divisors (see below), whose sum is σ = 1729800. Its totient is φ = 259840.

The previous prime is 684379. The next prime is 684407. The reversal of 684400 is 4486.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11571 + ... + 11629.

It is an arithmetic number, because the mean of its divisors is an integer number (28830).

2⁶⁸⁴⁴⁰⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 684400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (864900).

684400 is an abundant number, since it is smaller than the sum of its proper divisors (1045400).

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

684400 is a wasteful number, since it uses less digits than its factorization.

684400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 95 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 684400 is about 827.2847151979. The cubic root of 684400 is about 88.1258529837.

Adding to 684400 its reverse (4486), we get a palindrome (688886).

The spelling of 684400 in words is "six hundred eighty-four thousand, four hundred".