391986 has 64 divisors (see below), whose sum is σ = 1071360. Its totient is φ = 103680.

The previous prime is 391967. The next prime is 391987. The reversal of 391986 is 689193.

It is a self number, because there is not a number n which added to its sum of digits gives 391986.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391987) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6396 + ... + 6456.

It is an arithmetic number, because the mean of its divisors is an integer number (16740).

2³⁹¹⁹⁸⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391986, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (535680).

391986 is an abundant number, since it is smaller than the sum of its proper divisors (679374).

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

391986 is a wasteful number, since it uses less digits than its factorization.

391986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96 (or 90 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 391986 is about 626.0878532602. The cubic root of 391986 is about 73.1852429268.

It can be divided in two parts, 39198 and 6, that added together give a square (39204 = 198²).

The spelling of 391986 in words is "three hundred ninety-one thousand, nine hundred eighty-six".