687744 has 64 divisors (see below), whose sum is σ = 2040000. Its totient is φ = 228096.

The previous prime is 687737. The next prime is 687749. The reversal of 687744 is 447786.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 687699 and 687708.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 687744.

It is not an unprimeable number, because it can be changed into a prime (687749) by changing a digit.

687744 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 7 ways as a sum of consecutive naturals, for example, 3357 + ... + 3555.

It is an arithmetic number, because the mean of its divisors is an integer number (31875).

2⁶⁸⁷⁷⁴⁴ is an apocalyptic number.

687744 is a gapful number since it is divisible by the number (64) 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 687744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1020000).

687744 is an abundant number, since it is smaller than the sum of its proper divisors (1352256).

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

687744 is a wasteful number, since it uses less digits than its factorization.

687744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222 (or 204 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The square root of 687744 is about 829.3033220722. The cubic root of 687744 is about 88.2691484208.

It can be divided in two parts, 687 and 744, that added together give a triangular number (1431 = T₅₃).

The spelling of 687744 in words is "six hundred eighty-seven thousand, seven hundred forty-four".