684990 has 64 divisors (see below), whose sum is σ = 1900800. Its totient is φ = 175392.

The previous prime is 684989. The next prime is 685001. The reversal of 684990 is 99486.

It is a super-2 number, since 2×684990² = 938422600200, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11581 + ... + 11639.

It is an arithmetic number, because the mean of its divisors is an integer number (29700).

2⁶⁸⁴⁹⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 684990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (950400).

684990 is an abundant number, since it is smaller than the sum of its proper divisors (1215810).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

684990 is a wasteful number, since it uses less digits than its factorization.

684990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118 (or 112 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 684990 is about 827.6412266194. The cubic root of 684990 is about 88.1511692313.

The spelling of 684990 in words is "six hundred eighty-four thousand, nine hundred ninety".