684688221 has 36 divisors (see below), whose sum is σ = 1193092992. Its totient is φ = 391243608.

The previous prime is 684688211. The next prime is 684688223. The reversal of 684688221 is 122886486.

It is not a de Polignac number, because 684688221 - 2⁵ = 684688189 is a prime.

It is a super-2 number, since 2×684688221² = 937595919952289682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684688223) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 16845 + ... + 40658.

It is an arithmetic number, because the mean of its divisors is an integer number (33141472).

Almost surely, 2^684688221 is an apocalyptic number.

It is an amenable number.

684688221 is a deficient number, since it is larger than the sum of its proper divisors (508404771).

684688221 is an equidigital number, since it uses as much as digits as its factorization.

684688221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57532 (or 57513 counting only the distinct ones).

The product of its digits is 294912, while the sum is 45.

The square root of 684688221 is about 26166.5477470758. The cubic root of 684688221 is about 881.3822204507.

The spelling of 684688221 in words is "six hundred eighty-four million, six hundred eighty-eight thousand, two hundred twenty-one".