678931891 has 16 divisors (see below), whose sum is σ = 763451136. Its totient is φ = 598500000.

The previous prime is 678931889. The next prime is 678931919. The reversal of 678931891 is 198139876.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 678931891 - 2¹ = 678931889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (678931801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40516 + ... + 54766.

It is an arithmetic number, because the mean of its divisors is an integer number (47715696).

Almost surely, 2^678931891 is an apocalyptic number.

678931891 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

678931891 is a deficient number, since it is larger than the sum of its proper divisors (84519245).

678931891 is a wasteful number, since it uses less digits than its factorization.

678931891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14394.

The product of its digits is 653184, while the sum is 52.

The square root of 678931891 is about 26056.3215170522. The cubic root of 678931891 is about 878.9052722364.

The spelling of 678931891 in words is "six hundred seventy-eight million, nine hundred thirty-one thousand, eight hundred ninety-one".