678387921 has 8 divisors (see below), whose sum is σ = 943844160. Its totient is φ = 432595152.

The previous prime is 678387887. The next prime is 678387943. The reversal of 678387921 is 129783876.

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

It is not a de Polignac number, because 678387921 - 2²⁵ = 644833489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (678317921) 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, 4915786 + ... + 4915923.

It is an arithmetic number, because the mean of its divisors is an integer number (117980520).

Almost surely, 2^678387921 is an apocalyptic number.

It is an amenable number.

678387921 is a deficient number, since it is larger than the sum of its proper divisors (265456239).

678387921 is a wasteful number, since it uses less digits than its factorization.

678387921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9831735.

The product of its digits is 1016064, while the sum is 51.

The square root of 678387921 is about 26045.8810755175. The cubic root of 678387921 is about 878.6704790019.

The spelling of 678387921 in words is "six hundred seventy-eight million, three hundred eighty-seven thousand, nine hundred twenty-one".