4081991 has 2 divisors, whose sum is σ = 4081992. Its totient is φ = 4081990.

The previous prime is 4081969. The next prime is 4081999. The reversal of 4081991 is 1991804.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4081991 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4081999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2040995 + 2040996.

It is an arithmetic number, because the mean of its divisors is an integer number (2040996).

Almost surely, 2^4081991 is an apocalyptic number.

4081991 is a deficient number, since it is larger than the sum of its proper divisors (1).

4081991 is an equidigital number, since it uses as much as digits as its factorization.

4081991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 4081991 is about 2020.3937735006. The cubic root of 4081991 is about 159.8173827936.

The spelling of 4081991 in words is "four million, eighty-one thousand, nine hundred ninety-one".