391681646 has 8 divisors (see below), whose sum is σ = 595570944. Its totient is φ = 193158000.

The previous prime is 391681639. The next prime is 391681657. The reversal of 391681646 is 646186193.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 391681597 and 391681606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1341230 + ... + 1341521.

It is an arithmetic number, because the mean of its divisors is an integer number (74446368).

Almost surely, 2^391681646 is an apocalyptic number.

391681646 is a deficient number, since it is larger than the sum of its proper divisors (203889298).

391681646 is a wasteful number, since it uses less digits than its factorization.

391681646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2682826.

The product of its digits is 186624, while the sum is 44.

The square root of 391681646 is about 19790.9485876751. The cubic root of 391681646 is about 731.6629668148.

The spelling of 391681646 in words is "three hundred ninety-one million, six hundred eighty-one thousand, six hundred forty-six".