391864 has 32 divisors (see below), whose sum is σ = 825840. Its totient is φ = 172800.

The previous prime is 391861. The next prime is 391873. The reversal of 391864 is 468193.

391864 = T₁₁ + T₁₂ + ... + T₁₃₂.

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 polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5332 + ... + 5404.

391864 is a Friedman number, since it can be written as 4*((8-1)^6-3^9), using all its digits and the basic arithmetic operations.

2³⁹¹⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (412920).

391864 is an abundant number, since it is smaller than the sum of its proper divisors (433976).

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

391864 is a wasteful number, since it uses less digits than its factorization.

391864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 147 counting only the distinct ones).

The product of its digits is 5184, while the sum is 31.

The square root of 391864 is about 625.9904152621. The cubic root of 391864 is about 73.1776495212.

The spelling of 391864 in words is "three hundred ninety-one thousand, eight hundred sixty-four".