2091491 has 4 divisors (see below), whose sum is σ = 2127000. Its totient is φ = 2055984.

The previous prime is 2091487. The next prime is 2091497. The reversal of 2091491 is 1941902.

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

It is a cyclic number.

It is not a de Polignac number, because 2091491 - 2² = 2091487 is a prime.

It is an Ulam number.

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 2091491.

It is not an unprimeable number, because it can be changed into a prime (2091497) 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, 17666 + ... + 17783.

It is an arithmetic number, because the mean of its divisors is an integer number (531750).

2^2091491 is an apocalyptic number.

2091491 is a deficient number, since it is larger than the sum of its proper divisors (35509).

2091491 is an equidigital number, since it uses as much as digits as its factorization.

2091491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35508.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 2091491 is about 1446.1988106758. The cubic root of 2091491 is about 127.8847228724.

The spelling of 2091491 in words is "two million, ninety-one thousand, four hundred ninety-one".