684638 has 4 divisors (see below), whose sum is σ = 1026960. Its totient is φ = 342318.

The previous prime is 684637. The next prime is 684643. The reversal of 684638 is 836486.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 684598 and 684607.

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 684638.

It is not an unprimeable number, because it can be changed into a prime (684637) 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 as a sum of consecutive naturals, namely, 171158 + ... + 171161.

It is an arithmetic number, because the mean of its divisors is an integer number (256740).

2⁶⁸⁴⁶³⁸ is an apocalyptic number.

684638 is a deficient number, since it is larger than the sum of its proper divisors (342322).

684638 is a wasteful number, since it uses less digits than its factorization.

684638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342321.

The product of its digits is 27648, while the sum is 35.

The square root of 684638 is about 827.4285467640. The cubic root of 684638 is about 88.1360670507.

The spelling of 684638 in words is "six hundred eighty-four thousand, six hundred thirty-eight".