3811991 has 4 divisors (see below), whose sum is σ = 3816984. Its totient is φ = 3807000.

The previous prime is 3811979. The next prime is 3812023. The reversal of 3811991 is 1991183.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991183 = 251 ⋅7933.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3811991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3811921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1085 + ... + 2966.

It is an arithmetic number, because the mean of its divisors is an integer number (954246).

Almost surely, 2^3811991 is an apocalyptic number.

3811991 is a deficient number, since it is larger than the sum of its proper divisors (4993).

3811991 is an equidigital number, since it uses as much as digits as its factorization.

3811991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4992.

The product of its digits is 1944, while the sum is 32.

The square root of 3811991 is about 1952.4320730822. The cubic root of 3811991 is about 156.2130417122.

The spelling of 3811991 in words is "three million, eight hundred eleven thousand, nine hundred ninety-one".