391806 has 12 divisors (see below), whose sum is σ = 848952. Its totient is φ = 130596.

The previous prime is 391801. The next prime is 391817. The reversal of 391806 is 608193.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 391806.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391806.

It is not an unprimeable number, because it can be changed into a prime (391801) by changing a digit.

391806 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10866 + ... + 10901.

It is an arithmetic number, because the mean of its divisors is an integer number (70746).

2³⁹¹⁸⁰⁶ is an apocalyptic number.

391806 is an abundant number, since it is smaller than the sum of its proper divisors (457146).

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

391806 is a wasteful number, since it uses less digits than its factorization.

391806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21775 (or 21772 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 391806 is about 625.9440869598. The cubic root of 391806 is about 73.1740389887.

Adding to 391806 its reverse (608193), we get a palindrome (999999).

It can be divided in two parts, 3 and 91806, that added together give a square (91809 = 303²).

The spelling of 391806 in words is "three hundred ninety-one thousand, eight hundred six".