391516993 has 8 divisors (see below), whose sum is σ = 447805440. Its totient is φ = 335317920.

The previous prime is 391516981. The next prime is 391517029. The reversal of 391516993 is 399615193.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 391516993 - 2⁹ = 391516481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391516693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12673 + ... + 30718.

It is an arithmetic number, because the mean of its divisors is an integer number (55975680).

Almost surely, 2^391516993 is an apocalyptic number.

It is an amenable number.

391516993 is a deficient number, since it is larger than the sum of its proper divisors (56288447).

391516993 is a wasteful number, since it uses less digits than its factorization.

391516993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44687.

The product of its digits is 196830, while the sum is 46.

The square root of 391516993 is about 19786.7883447517. The cubic root of 391516993 is about 731.5604282790.

The spelling of 391516993 in words is "three hundred ninety-one million, five hundred sixteen thousand, nine hundred ninety-three".