391665642 has 16 divisors (see below), whose sum is σ = 783606432. Its totient is φ = 130509360.

The previous prime is 391665623. The next prime is 391665679. The reversal of 391665642 is 246566193.

It is a junction number, because it is equal to n+sod(n) for n = 391665594 and 391665603.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10188 + ... + 29784.

It is an arithmetic number, because the mean of its divisors is an integer number (48975402).

Almost surely, 2^391665642 is an apocalyptic number.

391665642 is an abundant number, since it is smaller than the sum of its proper divisors (391940790).

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

391665642 is a wasteful number, since it uses less digits than its factorization.

391665642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22933.

The product of its digits is 233280, while the sum is 42.

The square root of 391665642 is about 19790.5442572962. The cubic root of 391665642 is about 731.6530014992.

The spelling of 391665642 in words is "three hundred ninety-one million, six hundred sixty-five thousand, six hundred forty-two".