688720 has 20 divisors (see below), whose sum is σ = 1601460. Its totient is φ = 275456.

The previous prime is 688717. The next prime is 688729. The reversal of 688720 is 27886.

It can be written as a sum of positive squares in 2 ways, for example, as 204304 + 484416 = 452^2 + 696^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688729) 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, 4225 + ... + 4384.

It is an arithmetic number, because the mean of its divisors is an integer number (80073).

2⁶⁸⁸⁷²⁰ is an apocalyptic number.

It is an amenable number.

688720 is an abundant number, since it is smaller than the sum of its proper divisors (912740).

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

688720 is a wasteful number, since it uses less digits than its factorization.

688720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8622 (or 8616 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 688720 is about 829.8915591811. The cubic root of 688720 is about 88.3108838960.

The spelling of 688720 in words is "six hundred eighty-eight thousand, seven hundred twenty".