684021 has 8 divisors (see below), whose sum is σ = 982240. Its totient is φ = 420912.

The previous prime is 684017. The next prime is 684037. The reversal of 684021 is 120486.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 684021 - 2² = 684017 is a prime.

It is a Duffinian number.

684021 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8731 + ... + 8808.

It is an arithmetic number, because the mean of its divisors is an integer number (122780).

2⁶⁸⁴⁰²¹ is an apocalyptic number.

It is an amenable number.

684021 is a deficient number, since it is larger than the sum of its proper divisors (298219).

684021 is a wasteful number, since it uses less digits than its factorization.

684021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17555.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 684021 is about 827.0556208623. The cubic root of 684021 is about 88.1095828369.

The spelling of 684021 in words is "six hundred eighty-four thousand, twenty-one".