394471991 has 4 divisors (see below), whose sum is σ = 394719984. Its totient is φ = 394224000.

The previous prime is 394471967. The next prime is 394471997. The reversal of 394471991 is 199174493.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199174493 = 7 ⋅28453499.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-394471991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (394471997) 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, 121595 + ... + 124796.

It is an arithmetic number, because the mean of its divisors is an integer number (98679996).

Almost surely, 2^394471991 is an apocalyptic number.

394471991 is a deficient number, since it is larger than the sum of its proper divisors (247993).

394471991 is a wasteful number, since it uses less digits than its factorization.

394471991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247992.

The product of its digits is 244944, while the sum is 47.

The square root of 394471991 is about 19861.3189642581. The cubic root of 394471991 is about 733.3963159175.

The spelling of 394471991 in words is "three hundred ninety-four million, four hundred seventy-one thousand, nine hundred ninety-one".