684839 has 4 divisors (see below), whose sum is σ = 687240. Its totient is φ = 682440.

The previous prime is 684829. The next prime is 684841. The reversal of 684839 is 938486.

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

It is a cyclic number.

It is not a de Polignac number, because 684839 - 2¹⁶ = 619303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684809) 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 3 ways as a sum of consecutive naturals, for example, 704 + ... + 1365.

It is an arithmetic number, because the mean of its divisors is an integer number (171810).

2⁶⁸⁴⁸³⁹ is an apocalyptic number.

684839 is a deficient number, since it is larger than the sum of its proper divisors (2401).

684839 is a wasteful number, since it uses less digits than its factorization.

684839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2400.

The product of its digits is 41472, while the sum is 38.

The square root of 684839 is about 827.5499984895. The cubic root of 684839 is about 88.1446913729.

The spelling of 684839 in words is "six hundred eighty-four thousand, eight hundred thirty-nine".