3991312 has 40 divisors (see below), whose sum is σ = 8610560. Its totient is φ = 1779840.

The previous prime is 3991297. The next prime is 3991313. The reversal of 3991312 is 2131993.

3991312 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (3991313) 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, 6139 + ... + 6757.

It is an arithmetic number, because the mean of its divisors is an integer number (215264).

Almost surely, 2^3991312 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 3991312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4305280).

3991312 is an abundant number, since it is smaller than the sum of its proper divisors (4619248).

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

3991312 is a wasteful number, since it uses less digits than its factorization.

3991312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671 (or 665 counting only the distinct ones).

The product of its digits is 1458, while the sum is 28.

The square root of 3991312 is about 1997.8268193214. The cubic root of 3991312 is about 158.6250940524.

It can be divided in two parts, 399 and 1312, that added together give a triangular number (1711 = T₅₈).

The spelling of 3991312 in words is "three million, nine hundred ninety-one thousand, three hundred twelve".