3991842 has 40 divisors (see below), whose sum is σ = 9178092. Its totient is φ = 1296000.

The previous prime is 3991831. The next prime is 3991853. The reversal of 3991842 is 2481993.

3991842 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (3991831) and next prime (3991853).

It can be written as a sum of positive squares in 2 ways, for example, as 3956121 + 35721 = 1989^2 + 189^2 .

It is a junction number, because it is equal to n+sod(n) for n = 3991797 and 3991806.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6342 + ... + 6942.

Almost surely, 2^3991842 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3991842, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4589046).

3991842 is an abundant number, since it is smaller than the sum of its proper divisors (5186250).

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

3991842 is a wasteful number, since it uses less digits than its factorization.

3991842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656 (or 647 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 3991842 is about 1997.9594590482. The cubic root of 3991842 is about 158.6321149333.

The spelling of 3991842 in words is "three million, nine hundred ninety-one thousand, eight hundred forty-two".