684240 has 40 divisors (see below), whose sum is σ = 2121888. Its totient is φ = 182400.

The previous prime is 684239. The next prime is 684269. The reversal of 684240 is 42486.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 684240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1186 + ... + 1665.

2⁶⁸⁴²⁴⁰ is an apocalyptic number.

684240 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

684240 is an abundant number, since it is smaller than the sum of its proper divisors (1437648).

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

684240 is a wasteful number, since it uses less digits than its factorization.

684240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2867 (or 2861 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 684240 is about 827.1880076500. The cubic root of 684240 is about 88.1189850530.

The spelling of 684240 in words is "six hundred eighty-four thousand, two hundred forty".