3991765 has 16 divisors (see below), whose sum is σ = 5061888. Its totient is φ = 3015936.

The previous prime is 3991751. The next prime is 3991807. The reversal of 3991765 is 5671993.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3991765 is a prime.

It is a Duffinian number.

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, 11677 + ... + 12013.

It is an arithmetic number, because the mean of its divisors is an integer number (316368).

Almost surely, 2^3991765 is an apocalyptic number.

It is an amenable number.

3991765 is a deficient number, since it is larger than the sum of its proper divisors (1070123).

3991765 is a wasteful number, since it uses less digits than its factorization.

3991765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 468.

The product of its digits is 51030, while the sum is 40.

The square root of 3991765 is about 1997.9401892950. The cubic root of 3991765 is about 158.6310949571.

Subtracting from 3991765 its sum of digits (40), we obtain a triangular number (3991725 = T₂₈₂₅).

The spelling of 3991765 in words is "three million, nine hundred ninety-one thousand, seven hundred sixty-five".