688686840 has 256 divisors, whose sum is σ = 2390169600. Its totient is φ = 176256000.

The previous prime is 688686833. The next prime is 688686841. The reversal of 688686840 is 48686886.

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 (688686841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4560765 + ... + 4560915.

It is an arithmetic number, because the mean of its divisors is an integer number (9336600).

Almost surely, 2^688686840 is an apocalyptic number.

688686840 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 688686840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1195084800).

688686840 is an abundant number, since it is smaller than the sum of its proper divisors (1701482760).

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

688686840 is a wasteful number, since it uses less digits than its factorization.

688686840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 3538944, while the sum is 54.

The square root of 688686840 is about 26242.8435959215. The cubic root of 688686840 is about 883.0946656337.

The spelling of 688686840 in words is "six hundred eighty-eight million, six hundred eighty-six thousand, eight hundred forty".