391969913 has 4 divisors (see below), whose sum is σ = 397490688. Its totient is φ = 386449140.

The previous prime is 391969909. The next prime is 391969939. The reversal of 391969913 is 319969193.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 319969193 = 241 ⋅1327673.

It is a cyclic number.

It is not a de Polignac number, because 391969913 - 2² = 391969909 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391969813) 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 3 ways as a sum of consecutive naturals, for example, 2760281 + ... + 2760422.

It is an arithmetic number, because the mean of its divisors is an integer number (99372672).

Almost surely, 2^391969913 is an apocalyptic number.

It is an amenable number.

391969913 is a deficient number, since it is larger than the sum of its proper divisors (5520775).

391969913 is an equidigital number, since it uses as much as digits as its factorization.

391969913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5520774.

The product of its digits is 354294, while the sum is 50.

The square root of 391969913 is about 19798.2300471532. The cubic root of 391969913 is about 731.8424174557.

The spelling of 391969913 in words is "three hundred ninety-one million, nine hundred sixty-nine thousand, nine hundred thirteen".