2191591 has 4 divisors (see below), whose sum is σ = 2196184. Its totient is φ = 2187000.

The previous prime is 2191583. The next prime is 2191619. The reversal of 2191591 is 1951912.

2191591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a 3-Lehmer number, since φ(2191591) divides (2191591-1)³.

It is a cyclic number.

It is not a de Polignac number, because 2191591 - 2³ = 2191583 is a prime.

It is a super-2 number, since 2×2191591² = 9606142222562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2191561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1485 + ... + 2566.

It is an arithmetic number, because the mean of its divisors is an integer number (549046).

2^2191591 is an apocalyptic number.

2191591 is a deficient number, since it is larger than the sum of its proper divisors (4593).

2191591 is an equidigital number, since it uses as much as digits as its factorization.

2191591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4592.

The product of its digits is 810, while the sum is 28.

The square root of 2191591 is about 1480.4023101846. The cubic root of 2191591 is about 129.8932259358.

The spelling of 2191591 in words is "two million, one hundred ninety-one thousand, five hundred ninety-one".