391985646 has 32 divisors (see below), whose sum is σ = 852653088. Its totient is φ = 119414400.

The previous prime is 391985621. The next prime is 391985647. The reversal of 391985646 is 646589193.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391985647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17001 + ... + 32756.

It is an arithmetic number, because the mean of its divisors is an integer number (26645409).

Almost surely, 2^391985646 is an apocalyptic number.

391985646 is an abundant number, since it is smaller than the sum of its proper divisors (460667442).

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

391985646 is a wasteful number, since it uses less digits than its factorization.

391985646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49876.

The product of its digits is 1399680, while the sum is 51.

The square root of 391985646 is about 19798.6273766643. The cubic root of 391985646 is about 731.8522089578.

It can be divided in two parts, 39198 and 5646, that added together give a palindrome (44844).

The spelling of 391985646 in words is "three hundred ninety-one million, nine hundred eighty-five thousand, six hundred forty-six".