3991788 has 48 divisors (see below), whose sum is σ = 10805760. Its totient is φ = 1271952.

The previous prime is 3991751. The next prime is 3991807. The reversal of 3991788 is 8871993.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1681 + ... + 3287.

It is an arithmetic number, because the mean of its divisors is an integer number (225120).

Almost surely, 2^3991788 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 3991788, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5402880).

3991788 is an abundant number, since it is smaller than the sum of its proper divisors (6813972).

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

3991788 is a wasteful number, since it uses less digits than its factorization.

3991788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1643 (or 1635 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 3991788 is about 1997.9459452147. The cubic root of 3991788 is about 158.6313996267.

It can be divided in two parts, 399 and 1788, that added together give a 7-th power (2187 = 3⁷).

The spelling of 3991788 in words is "three million, nine hundred ninety-one thousand, seven hundred eighty-eight".