391866 has 16 divisors (see below), whose sum is σ = 789888. Its totient is φ = 129600.

The previous prime is 391861. The next prime is 391873. The reversal of 391866 is 668193.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391861) 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, 1311 + ... + 1581.

It is an arithmetic number, because the mean of its divisors is an integer number (49368).

2³⁹¹⁸⁶⁶ is an apocalyptic number.

391866 is an abundant number, since it is smaller than the sum of its proper divisors (398022).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391866 is a wasteful number, since it uses less digits than its factorization.

391866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517.

The product of its digits is 7776, while the sum is 33.

The square root of 391866 is about 625.9920127286. The cubic root of 391866 is about 73.1777740160.

The spelling of 391866 in words is "three hundred ninety-one thousand, eight hundred sixty-six".