678115821 has 4 divisors (see below), whose sum is σ = 904154432. Its totient is φ = 452077212.

The previous prime is 678115811. The next prime is 678115843. The reversal of 678115821 is 128511876.

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 678115821 - 2⁹ = 678115309 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 678115821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (678115811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 113019301 + ... + 113019306.

It is an arithmetic number, because the mean of its divisors is an integer number (226038608).

Almost surely, 2^678115821 is an apocalyptic number.

It is an amenable number.

678115821 is a deficient number, since it is larger than the sum of its proper divisors (226038611).

678115821 is a wasteful number, since it uses less digits than its factorization.

678115821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226038610.

The product of its digits is 26880, while the sum is 39.

The square root of 678115821 is about 26040.6570769633. The cubic root of 678115821 is about 878.5529856510.

The spelling of 678115821 in words is "six hundred seventy-eight million, one hundred fifteen thousand, eight hundred twenty-one".