391278971 has 4 divisors (see below), whose sum is σ = 393327744. Its totient is φ = 389230200.

The previous prime is 391278961. The next prime is 391278983. The reversal of 391278971 is 179872193.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 179872193 = 167 ⋅1077079.

It is a cyclic number.

It is not a de Polignac number, because 391278971 - 2²⁶ = 324170107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391278911) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1024100 + ... + 1024481.

It is an arithmetic number, because the mean of its divisors is an integer number (98331936).

Almost surely, 2^391278971 is an apocalyptic number.

391278971 is a deficient number, since it is larger than the sum of its proper divisors (2048773).

391278971 is a wasteful number, since it uses less digits than its factorization.

391278971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2048772.

The product of its digits is 190512, while the sum is 47.

The square root of 391278971 is about 19780.7727604358. The cubic root of 391278971 is about 731.4121479761.

The spelling of 391278971 in words is "three hundred ninety-one million, two hundred seventy-eight thousand, nine hundred seventy-one".