684921 has 4 divisors (see below), whose sum is σ = 913232. Its totient is φ = 456612.

The previous prime is 684889. The next prime is 684923. The reversal of 684921 is 129486.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 684921 - 2⁵ = 684889 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (684923) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114151 + ... + 114156.

It is an arithmetic number, because the mean of its divisors is an integer number (228308).

2⁶⁸⁴⁹²¹ is an apocalyptic number.

It is an amenable number.

684921 is a deficient number, since it is larger than the sum of its proper divisors (228311).

684921 is a wasteful number, since it uses less digits than its factorization.

684921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228310.

The product of its digits is 3456, while the sum is 30.

The square root of 684921 is about 827.5995408409. The cubic root of 684921 is about 88.1482092684.

The spelling of 684921 in words is "six hundred eighty-four thousand, nine hundred twenty-one".