2131891 has 4 divisors (see below), whose sum is σ = 2134872. Its totient is φ = 2128912.

The previous prime is 2131867. The next prime is 2131907. The reversal of 2131891 is 1981312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 2131891 - 2⁵ = 2131859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2131291) 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, 300 + ... + 2086.

It is an arithmetic number, because the mean of its divisors is an integer number (533718).

2^2131891 is an apocalyptic number.

2131891 is a deficient number, since it is larger than the sum of its proper divisors (2981).

2131891 is a wasteful number, since it uses less digits than its factorization.

2131891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2980.

The product of its digits is 432, while the sum is 25.

The square root of 2131891 is about 1460.0996541332. The cubic root of 2131891 is about 128.7028997917.

The spelling of 2131891 in words is "two million, one hundred thirty-one thousand, eight hundred ninety-one".