688371840 has 384 divisors, whose sum is σ = 2656508400. Its totient is φ = 163086336.

The previous prime is 688371799. The next prime is 688371847. The reversal of 688371840 is 48173886.

It can be written as a sum of positive squares in 8 ways, for example, as 44836416 + 643535424 = 6696^2 + 25368^2 .

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688371847) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 2171362 + ... + 2171678.

Almost surely, 2^688371840 is an apocalyptic number.

688371840 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 688371840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1328254200).

688371840 is an abundant number, since it is smaller than the sum of its proper divisors (1968136560).

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

688371840 is a wasteful number, since it uses less digits than its factorization.

688371840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384 (or 369 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The square root of 688371840 is about 26236.8412732936. The cubic root of 688371840 is about 882.9600048920.

The spelling of 688371840 in words is "six hundred eighty-eight million, three hundred seventy-one thousand, eight hundred forty".