2099991 has 16 divisors (see below), whose sum is σ = 2917376. Its totient is φ = 1342656.

The previous prime is 2099963. The next prime is 2100001. The reversal of 2099991 is 1999902.

It is a happy number.

It is not a de Polignac number, because 2099991 - 2⁶ = 2099927 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2099921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9306 + ... + 9528.

It is an arithmetic number, because the mean of its divisors is an integer number (182336).

2^2099991 is an apocalyptic number.

2099991 is a deficient number, since it is larger than the sum of its proper divisors (817385).

2099991 is a wasteful number, since it uses less digits than its factorization.

2099991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342.

The product of its (nonzero) digits is 13122, while the sum is 39.

The square root of 2099991 is about 1449.1345693206. The cubic root of 2099991 is about 128.0577335586.

The spelling of 2099991 in words is "two million, ninety-nine thousand, nine hundred ninety-one".