678921 has 4 divisors (see below), whose sum is σ = 905232. Its totient is φ = 452612.

The previous prime is 678907. The next prime is 678941. The reversal of 678921 is 129876.

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 a cyclic number.

It is not a de Polignac number, because 678921 - 2⁹ = 678409 is a prime.

It is a D-number.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 678921.

It is not an unprimeable number, because it can be changed into a prime (678901) 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, 113151 + ... + 113156.

It is an arithmetic number, because the mean of its divisors is an integer number (226308).

2⁶⁷⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

678921 is a deficient number, since it is larger than the sum of its proper divisors (226311).

678921 is a wasteful number, since it uses less digits than its factorization.

678921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226310.

The product of its digits is 6048, while the sum is 33.

The square root of 678921 is about 823.9666255377. The cubic root of 678921 is about 87.8900572595.

The spelling of 678921 in words is "six hundred seventy-eight thousand, nine hundred twenty-one".