688909806 has 64 divisors (see below), whose sum is σ = 1652797440. Its totient is φ = 211442400.

The previous prime is 688909801. The next prime is 688909889. The reversal of 688909806 is 608909886.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688909801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 352131 + ... + 354081.

It is an arithmetic number, because the mean of its divisors is an integer number (25824960).

Almost surely, 2^688909806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 688909806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (826398720).

688909806 is an abundant number, since it is smaller than the sum of its proper divisors (963887634).

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

688909806 is a wasteful number, since it uses less digits than its factorization.

688909806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2478 (or 2472 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

The square root of 688909806 is about 26247.0913817131. The cubic root of 688909806 is about 883.1899575373.

The spelling of 688909806 in words is "six hundred eighty-eight million, nine hundred nine thousand, eight hundred six".