685440 has 192 divisors, whose sum is σ = 2864160. Its totient is φ = 147456.

The previous prime is 685429. The next prime is 685453. The reversal of 685440 is 44586.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is an unprimeable number.

685440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40312 + ... + 40328.

2⁶⁸⁵⁴⁴⁰ is an apocalyptic number.

685440 is a gapful number since it is divisible by the number (60) 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 685440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1432080).

685440 is an abundant number, since it is smaller than the sum of its proper divisors (2178720).

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

685440 is a wasteful number, since it uses less digits than its factorization.

685440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 685440 is about 827.9130389117. The cubic root of 685440 is about 88.1704684633.

The spelling of 685440 in words is "six hundred eighty-five thousand, four hundred forty".