688400240 has 80 divisors (see below), whose sum is σ = 1751137920. Its totient is φ = 249596160.

The previous prime is 688400239. The next prime is 688400243. The reversal of 688400240 is 42004886.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 688400197 and 688400206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688400243) 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 15 ways as a sum of consecutive naturals, for example, 367787 + ... + 369653.

It is an arithmetic number, because the mean of its divisors is an integer number (21889224).

Almost surely, 2^688400240 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 688400240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (875568960).

688400240 is an abundant number, since it is smaller than the sum of its proper divisors (1062737680).

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

688400240 is a wasteful number, since it uses less digits than its factorization.

688400240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2310 (or 2304 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 32.

The square root of 688400240 is about 26237.3824913996. The cubic root of 688400240 is about 882.9721474182.

The spelling of 688400240 in words is "six hundred eighty-eight million, four hundred thousand, two hundred forty".