688891 has 12 divisors (see below), whose sum is σ = 849528. Its totient is φ = 555072.

The previous prime is 688889. The next prime is 688907. The reversal of 688891 is 198886.

It is a happy number.

It is not a de Polignac number, because 688891 - 2¹ = 688889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (688861) 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 11 ways as a sum of consecutive naturals, for example, 420 + ... + 1246.

It is an arithmetic number, because the mean of its divisors is an integer number (70794).

2⁶⁸⁸⁸⁹¹ is an apocalyptic number.

688891 is a deficient number, since it is larger than the sum of its proper divisors (160637).

688891 is a wasteful number, since it uses less digits than its factorization.

688891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 858 (or 851 counting only the distinct ones).

The product of its digits is 27648, while the sum is 40.

The square root of 688891 is about 829.9945782955. The cubic root of 688891 is about 88.3181920965.

The spelling of 688891 in words is "six hundred eighty-eight thousand, eight hundred ninety-one".