391990 has 8 divisors (see below), whose sum is σ = 705600. Its totient is φ = 156792.

The previous prime is 391987. The next prime is 391999. The reversal of 391990 is 99193.

391990 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391999) 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 3 ways as a sum of consecutive naturals, for example, 19590 + ... + 19609.

It is an arithmetic number, because the mean of its divisors is an integer number (88200).

2³⁹¹⁹⁹⁰ is an apocalyptic number.

391990 is a deficient number, since it is larger than the sum of its proper divisors (313610).

391990 is a wasteful number, since it uses less digits than its factorization.

391990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39206.

The product of its (nonzero) digits is 2187, while the sum is 31.

The square root of 391990 is about 626.0910476919. The cubic root of 391990 is about 73.1854918643.

The spelling of 391990 in words is "three hundred ninety-one thousand, nine hundred ninety".