391878 has 40 divisors (see below), whose sum is σ = 914760. Its totient is φ = 125280.

The previous prime is 391873. The next prime is 391879. The reversal of 391878 is 878193.

It is a super-3 number, since 3×391878³ = 180540193433304456, which contains 333 as substring.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391873) by changing a digit.

391878 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 19 ways as a sum of consecutive naturals, for example, 6613 + ... + 6671.

It is an arithmetic number, because the mean of its divisors is an integer number (22869).

2³⁹¹⁸⁷⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391878, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (457380).

391878 is an abundant number, since it is smaller than the sum of its proper divisors (522882).

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

391878 is a wasteful number, since it uses less digits than its factorization.

391878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 105 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 391878 is about 626.0015974421. The cubic root of 391878 is about 73.1785209757.

The spelling of 391878 in words is "three hundred ninety-one thousand, eight hundred seventy-eight".