688638 has 8 divisors (see below), whose sum is σ = 1377288. Its totient is φ = 229544.

The previous prime is 688637. The next prime is 688657. The reversal of 688638 is 836886.

It is a sphenic number, since it is the product of 3 distinct primes.

688638 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 688596 and 688605.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 688638.

It is not an unprimeable number, because it can be changed into a prime (688631) 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 3 ways as a sum of consecutive naturals, for example, 57381 + ... + 57392.

It is an arithmetic number, because the mean of its divisors is an integer number (172161).

2⁶⁸⁸⁶³⁸ is an apocalyptic number.

688638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

688638 is a wasteful number, since it uses less digits than its factorization.

688638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114778.

The product of its digits is 55296, while the sum is 39.

The square root of 688638 is about 829.8421536654. The cubic root of 688638 is about 88.3073789496.

It can be divided in two parts, 688 and 638, that added together give a triangular number (1326 = T₅₁).

The spelling of 688638 in words is "six hundred eighty-eight thousand, six hundred thirty-eight".