678215691 has 12 divisors (see below), whose sum is σ = 981321432. Its totient is φ = 451370016.

The previous prime is 678215683. The next prime is 678215729. The reversal of 678215691 is 196512876.

678215691 is a `hidden beast` number, since 6 + 7 + 82 + 1 + 569 + 1 = 666.

It is not a de Polignac number, because 678215691 - 2³ = 678215683 is a prime.

It is not an unprimeable number, because it can be changed into a prime (678215641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58906 + ... + 69471.

It is an arithmetic number, because the mean of its divisors is an integer number (81776786).

Almost surely, 2^678215691 is an apocalyptic number.

678215691 is a deficient number, since it is larger than the sum of its proper divisors (303105741).

678215691 is a wasteful number, since it uses less digits than its factorization.

678215691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128970 (or 128967 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 678215691 is about 26042.5745847065. The cubic root of 678215691 is about 878.5961133769.

The spelling of 678215691 in words is "six hundred seventy-eight million, two hundred fifteen thousand, six hundred ninety-one".