2991891 has 12 divisors (see below), whose sum is σ = 4640712. Its totient is φ = 1709568.

The previous prime is 2991889. The next prime is 2991899. The reversal of 2991891 is 1981992.

It is a happy number.

It is not a de Polignac number, because 2991891 - 2¹ = 2991889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2991899) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10030 + ... + 10323.

It is an arithmetic number, because the mean of its divisors is an integer number (386726).

2^2991891 is an apocalyptic number.

2991891 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

2991891 is a deficient number, since it is larger than the sum of its proper divisors (1648821).

2991891 is a wasteful number, since it uses less digits than its factorization.

2991891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20370 (or 20363 counting only the distinct ones).

The product of its digits is 11664, while the sum is 39.

The square root of 2991891 is about 1729.7083569203. The cubic root of 2991891 is about 144.0948930864.

The spelling of 2991891 in words is "two million, nine hundred ninety-one thousand, eight hundred ninety-one".