3991491 has 32 divisors (see below), whose sum is σ = 6912000. Its totient is φ = 2275560.

The previous prime is 3991469. The next prime is 3991511. The reversal of 3991491 is 1941993.

It is not a de Polignac number, because 3991491 - 2⁹ = 3990979 is a prime.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (3991441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9046 + ... + 9476.

It is an arithmetic number, because the mean of its divisors is an integer number (216000).

Almost surely, 2^3991491 is an apocalyptic number.

3991491 is a deficient number, since it is larger than the sum of its proper divisors (2920509).

3991491 is an equidigital number, since it uses as much as digits as its factorization.

3991491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 461 (or 441 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 3991491 is about 1997.8716174970. The cubic root of 3991491 is about 158.6274653250.

The spelling of 3991491 in words is "three million, nine hundred ninety-one thousand, four hundred ninety-one".