391944639 has 8 divisors (see below), whose sum is σ = 553333680. Its totient is φ = 245926016.

The previous prime is 391944601. The next prime is 391944643. The reversal of 391944639 is 936449193.

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

It is a cyclic number.

It is not a de Polignac number, because 391944639 - 2⁸ = 391944383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391944659) 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 7 ways as a sum of consecutive naturals, for example, 3842544 + ... + 3842645.

It is an arithmetic number, because the mean of its divisors is an integer number (69166710).

Almost surely, 2^391944639 is an apocalyptic number.

391944639 is a deficient number, since it is larger than the sum of its proper divisors (161389041).

391944639 is a wasteful number, since it uses less digits than its factorization.

391944639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7685209.

The product of its digits is 629856, while the sum is 48.

The square root of 391944639 is about 19797.5917474828. The cubic root of 391944639 is about 731.8266875215.

The spelling of 391944639 in words is "three hundred ninety-one million, nine hundred forty-four thousand, six hundred thirty-nine".