688221 has 12 divisors (see below), whose sum is σ = 1015872. Its totient is φ = 448776.

The previous prime is 688217. The next prime is 688223. The reversal of 688221 is 122886.

It is not a de Polignac number, because 688221 - 2² = 688217 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 391 + ... + 1236.

It is an arithmetic number, because the mean of its divisors is an integer number (84656).

2⁶⁸⁸²²¹ is an apocalyptic number.

It is an amenable number.

688221 is a deficient number, since it is larger than the sum of its proper divisors (327651).

688221 is a wasteful number, since it uses less digits than its factorization.

688221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1680 (or 1677 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 688221 is about 829.5908630162. The cubic root of 688221 is about 88.2895507088.

It can be divided in two parts, 6882 and 21, that added together give a triangular number (6903 = T₁₁₇).

The spelling of 688221 in words is "six hundred eighty-eight thousand, two hundred twenty-one".