2111991 has 16 divisors (see below), whose sum is σ = 3243264. Its totient is φ = 1197504.

The previous prime is 2111971. The next prime is 2112007. The reversal of 2111991 is 1991112.

It is not a de Polignac number, because 2111991 - 2⁵ = 2111959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2111971) 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, 3115 + ... + 3731.

It is an arithmetic number, because the mean of its divisors is an integer number (202704).

2^2111991 is an apocalyptic number.

2111991 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

2111991 is a deficient number, since it is larger than the sum of its proper divisors (1131273).

2111991 is a wasteful number, since it uses less digits than its factorization.

2111991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790.

The product of its digits is 162, while the sum is 24.

The square root of 2111991 is about 1453.2690735029. The cubic root of 2111991 is about 128.3011909533.

The spelling of 2111991 in words is "two million, one hundred eleven thousand, nine hundred ninety-one".