678344921 has 4 divisors (see below), whose sum is σ = 680266932. Its totient is φ = 676422912.

The previous prime is 678344899. The next prime is 678344923. The reversal of 678344921 is 129443876.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 331640521 + 346704400 = 18211^2 + 18620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-678344921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (678344923) 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, 960476 + ... + 961181.

It is an arithmetic number, because the mean of its divisors is an integer number (170066733).

Almost surely, 2^678344921 is an apocalyptic number.

It is an amenable number.

678344921 is a deficient number, since it is larger than the sum of its proper divisors (1922011).

678344921 is a wasteful number, since it uses less digits than its factorization.

678344921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1922010.

The product of its digits is 290304, while the sum is 44.

The square root of 678344921 is about 26045.0555960244. The cubic root of 678344921 is about 878.6519136021.

The spelling of 678344921 in words is "six hundred seventy-eight million, three hundred forty-four thousand, nine hundred twenty-one".