391520947 has 4 divisors (see below), whose sum is σ = 393923080. Its totient is φ = 389118816.

The previous prime is 391520933. The next prime is 391520959. The reversal of 391520947 is 749025193.

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

It is not a de Polignac number, because 391520947 - 2¹¹ = 391518899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391527947) 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, 1200822 + ... + 1201147.

It is an arithmetic number, because the mean of its divisors is an integer number (98480770).

Almost surely, 2^391520947 is an apocalyptic number.

391520947 is a deficient number, since it is larger than the sum of its proper divisors (2402133).

391520947 is a wasteful number, since it uses less digits than its factorization.

391520947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2402132.

The product of its (nonzero) digits is 68040, while the sum is 40.

The square root of 391520947 is about 19786.8882596532. Note that the first 3 decimals coincide. The cubic root of 391520947 is about 731.5628909905.

The spelling of 391520947 in words is "three hundred ninety-one million, five hundred twenty thousand, nine hundred forty-seven".