684679221 has 12 divisors (see below), whose sum is σ = 1010023872. Its totient is φ = 446740776.

The previous prime is 684679217. The next prime is 684679223. The reversal of 684679221 is 122976486.

It is a happy number.

It is not a de Polignac number, because 684679221 - 2² = 684679217 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684679223) 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, 808891 + ... + 809736.

It is an arithmetic number, because the mean of its divisors is an integer number (84168656).

Almost surely, 2^684679221 is an apocalyptic number.

It is an amenable number.

684679221 is a deficient number, since it is larger than the sum of its proper divisors (325344651).

684679221 is a wasteful number, since it uses less digits than its factorization.

684679221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1618680 (or 1618677 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 684679221 is about 26166.3757712068. The cubic root of 684679221 is about 881.3783586080.

The spelling of 684679221 in words is "six hundred eighty-four million, six hundred seventy-nine thousand, two hundred twenty-one".