687691820 has 48 divisors (see below), whose sum is σ = 1533385728. Its totient is φ = 258170880.

The previous prime is 687691799. The next prime is 687691831. The reversal of 687691820 is 28196786.

687691820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127580 + ... + 132860.

It is an arithmetic number, because the mean of its divisors is an integer number (31945536).

Almost surely, 2^687691820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 687691820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (766692864).

687691820 is an abundant number, since it is smaller than the sum of its proper divisors (845693908).

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

687691820 is a wasteful number, since it uses less digits than its factorization.

687691820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5690 (or 5688 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 47.

The square root of 687691820 is about 26223.8788130208. The cubic root of 687691820 is about 882.6691600068.

The spelling of 687691820 in words is "six hundred eighty-seven million, six hundred ninety-one thousand, eight hundred twenty".