383991 has 4 divisors (see below), whose sum is σ = 511992. Its totient is φ = 255992.

The previous prime is 383987. The next prime is 384001. The reversal of 383991 is 199383.

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

It is a cyclic number.

It is not a de Polignac number, because 383991 - 2² = 383987 is a prime.

It is an Ulam number.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (383941) 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, 63996 + ... + 64001.

It is an arithmetic number, because the mean of its divisors is an integer number (127998).

2³⁸³⁹⁹¹ is an apocalyptic number.

383991 is a deficient number, since it is larger than the sum of its proper divisors (128001).

383991 is a wasteful number, since it uses less digits than its factorization.

383991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128000.

The product of its digits is 5832, while the sum is 33.

The square root of 383991 is about 619.6700735069. The cubic root of 383991 is about 72.6842558587.

The spelling of 383991 in words is "three hundred eighty-three thousand, nine hundred ninety-one".