687720 has 64 divisors (see below), whose sum is σ = 2255040. Its totient is φ = 166400.

The previous prime is 687707. The next prime is 687721. The reversal of 687720 is 27786.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687721) by changing a digit.

687720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1060 + ... + 1580.

It is an arithmetic number, because the mean of its divisors is an integer number (35235).

2⁶⁸⁷⁷²⁰ is an apocalyptic number.

687720 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 687720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1127520).

687720 is an abundant number, since it is smaller than the sum of its proper divisors (1567320).

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

687720 is a wasteful number, since it uses less digits than its factorization.

687720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546 (or 542 counting only the distinct ones).

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 687720 is about 829.2888519690. The cubic root of 687720 is about 88.2681216414.

The spelling of 687720 in words is "six hundred eighty-seven thousand, seven hundred twenty".