2106809591 has 4 divisors (see below), whose sum is σ = 2198410032. Its totient is φ = 2015209152.

The previous prime is 2106809587. The next prime is 2106809633. The reversal of 2106809591 is 1959086012.

It is a happy number.

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 2106809591 - 2² = 2106809587 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2106809581) 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, 45800186 + ... + 45800231.

It is an arithmetic number, because the mean of its divisors is an integer number (549602508).

Almost surely, 2^2106809591 is an apocalyptic number.

2106809591 is a deficient number, since it is larger than the sum of its proper divisors (91600441).

2106809591 is an equidigital number, since it uses as much as digits as its factorization.

2106809591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91600440.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 2106809591 is about 45899.9955446621. The cubic root of 2106809591 is about 1281.9618335150.

The spelling of 2106809591 in words is "two billion, one hundred six million, eight hundred nine thousand, five hundred ninety-one".