3991547 has 4 divisors (see below), whose sum is σ = 4561776. Its totient is φ = 3421320.

The previous prime is 3991543. The next prime is 3991571. The reversal of 3991547 is 7451993.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 3991547 - 2² = 3991543 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 3991547.

It is not an unprimeable number, because it can be changed into a prime (3991543) 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 in 3 ways as a sum of consecutive naturals, for example, 285104 + ... + 285117.

It is an arithmetic number, because the mean of its divisors is an integer number (1140444).

Almost surely, 2^3991547 is an apocalyptic number.

3991547 is a deficient number, since it is larger than the sum of its proper divisors (570229).

3991547 is an equidigital number, since it uses as much as digits as its factorization.

3991547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 570228.

The product of its digits is 34020, while the sum is 38.

The square root of 3991547 is about 1997.8856323624. The cubic root of 3991547 is about 158.6282071612.

The spelling of 3991547 in words is "three million, nine hundred ninety-one thousand, five hundred forty-seven".