684720 has 80 divisors (see below), whose sum is σ = 2365920. Its totient is φ = 182016.

The previous prime is 684713. The next prime is 684727. The reversal of 684720 is 27486.

It is an interprime number because it is at equal distance from previous prime (684713) and next prime (684727).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (684727) by changing a digit.

684720 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 15 ways as a sum of consecutive naturals, for example, 2002 + ... + 2318.

It is an arithmetic number, because the mean of its divisors is an integer number (29574).

2⁶⁸⁴⁷²⁰ is an apocalyptic number.

684720 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 684720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1182960).

684720 is an abundant number, since it is smaller than the sum of its proper divisors (1681200).

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

684720 is a wasteful number, since it uses less digits than its factorization.

684720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 684720 is about 827.4780963868. The cubic root of 684720 is about 88.1395856347.

The spelling of 684720 in words is "six hundred eighty-four thousand, seven hundred twenty".