391678668 has 36 divisors (see below), whose sum is σ = 997884160. Its totient is φ = 129530016.

The previous prime is 391678663. The next prime is 391678681. The reversal of 391678668 is 866876193.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (391678663) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38263 + ... + 47406.

Almost surely, 2^391678668 is an apocalyptic number.

It is an amenable number.

391678668 is an abundant number, since it is smaller than the sum of its proper divisors (606205492).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391678668 is a wasteful number, since it uses less digits than its factorization.

391678668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85806 (or 85801 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The square root of 391678668 is about 19790.8733511182. The cubic root of 391678668 is about 731.6611125045.

The spelling of 391678668 in words is "three hundred ninety-one million, six hundred seventy-eight thousand, six hundred sixty-eight".