391999479 has 4 divisors (see below), whose sum is σ = 522665976. Its totient is φ = 261332984.

The previous prime is 391999477. The next prime is 391999493. The reversal of 391999479 is 974999193.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 391999479 - 2¹ = 391999477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391999477) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65333244 + ... + 65333249.

It is an arithmetic number, because the mean of its divisors is an integer number (130666494).

Almost surely, 2^391999479 is an apocalyptic number.

391999479 is a deficient number, since it is larger than the sum of its proper divisors (130666497).

391999479 is a wasteful number, since it uses less digits than its factorization.

391999479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130666496.

The product of its digits is 4960116, while the sum is 60.

The square root of 391999479 is about 19798.9767159821. The cubic root of 391999479 is about 731.8608177701.

The spelling of 391999479 in words is "three hundred ninety-one million, nine hundred ninety-nine thousand, four hundred seventy-nine".