684390 has 32 divisors (see below), whose sum is σ = 1877760. Its totient is φ = 156384.

The previous prime is 684379. The next prime is 684407. The reversal of 684390 is 93486.

684390 = T₁₈₀ + T₁₈₁ + ... + T₂₁₄.

684390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

684390 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1420 + ... + 1839.

It is an arithmetic number, because the mean of its divisors is an integer number (58680).

2⁶⁸⁴³⁹⁰ is an apocalyptic number.

684390 is an abundant number, since it is smaller than the sum of its proper divisors (1193370).

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

684390 is a wasteful number, since it uses less digits than its factorization.

684390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3276.

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 684390 is about 827.2786713073. The cubic root of 684390 is about 88.1254237694.

The spelling of 684390 in words is "six hundred eighty-four thousand, three hundred ninety".