3991686 has 16 divisors (see below), whose sum is σ = 8004144. Its totient is φ = 1327104.

The previous prime is 3991681. The next prime is 3991693. The reversal of 3991686 is 6861993.

3991686 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991681) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 2886 + ... + 4038.

It is an arithmetic number, because the mean of its divisors is an integer number (500259).

Almost surely, 2^3991686 is an apocalyptic number.

3991686 is an abundant number, since it is smaller than the sum of its proper divisors (4012458).

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

3991686 is a wasteful number, since it uses less digits than its factorization.

3991686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1735.

The product of its digits is 69984, while the sum is 42.

The square root of 3991686 is about 1997.9204188355. The cubic root of 3991686 is about 158.6300484744.

The spelling of 3991686 in words is "three million, nine hundred ninety-one thousand, six hundred eighty-six".