3991785 has 24 divisors (see below), whose sum is σ = 7430976. Its totient is φ = 1824480.

The previous prime is 3991751. The next prime is 3991807. The reversal of 3991785 is 5871993.

It is a happy number.

It is not a de Polignac number, because 3991785 - 2¹⁰ = 3990761 is a prime.

It is a Curzon 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 23 ways as a sum of consecutive naturals, for example, 1981 + ... + 3450.

It is an arithmetic number, because the mean of its divisors is an integer number (309624).

Almost surely, 2^3991785 is an apocalyptic number.

3991785 is a gapful number since it is divisible by the number (35) formed by its first and last digit.

It is an amenable number.

3991785 is a deficient number, since it is larger than the sum of its proper divisors (3439191).

3991785 is a wasteful number, since it uses less digits than its factorization.

3991785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5453 (or 5446 counting only the distinct ones).

The product of its digits is 68040, while the sum is 42.

The square root of 3991785 is about 1997.9451944435. The cubic root of 3991785 is about 158.6313598872.

Adding to 3991785 its product of digits (68040), we get a triangular number (4059825 = T₂₈₄₉).

The spelling of 3991785 in words is "three million, nine hundred ninety-one thousand, seven hundred eighty-five".