3991543 has 2 divisors, whose sum is σ = 3991544. Its totient is φ = 3991542.

The previous prime is 3991517. The next prime is 3991571. The reversal of 3991543 is 3451993.

It is a weak prime.

It is an emirp because it is prime and its reverse (3451993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3991543 - 2⁵ = 3991511 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 3991499 and 3991508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3991573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995771 + 1995772.

It is an arithmetic number, because the mean of its divisors is an integer number (1995772).

Almost surely, 2^3991543 is an apocalyptic number.

3991543 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991543 is an equidigital number, since it uses as much as digits as its factorization.

3991543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14580, while the sum is 34.

The square root of 3991543 is about 1997.8846313038. The cubic root of 3991543 is about 158.6281541731.

The spelling of 3991543 in words is "three million, nine hundred ninety-one thousand, five hundred forty-three".