391233991 has 8 divisors (see below), whose sum is σ = 396648000. Its totient is φ = 385831680.

The previous prime is 391233977. The next prime is 391234003. The reversal of 391233991 is 199332193.

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

It is a cyclic number.

It is not a de Polignac number, because 391233991 - 2¹⁹ = 390709703 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 (391233901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80511 + ... + 85231.

It is an arithmetic number, because the mean of its divisors is an integer number (49581000).

Almost surely, 2^391233991 is an apocalyptic number.

391233991 is a deficient number, since it is larger than the sum of its proper divisors (5414009).

391233991 is a wasteful number, since it uses less digits than its factorization.

391233991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5849.

The product of its digits is 39366, while the sum is 40.

The square root of 391233991 is about 19779.6357650994. The cubic root of 391233991 is about 731.3841200799.

The spelling of 391233991 in words is "three hundred ninety-one million, two hundred thirty-three thousand, nine hundred ninety-one".