2215891 has 4 divisors (see below), whose sum is σ = 2249032. Its totient is φ = 2182752.

The previous prime is 2215867. The next prime is 2215901. The reversal of 2215891 is 1985122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1985122 = 2 ⋅992561.

It is a cyclic number.

It is not a de Polignac number, because 2215891 - 2⁹ = 2215379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2215091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16470 + ... + 16603.

It is an arithmetic number, because the mean of its divisors is an integer number (562258).

2^2215891 is an apocalyptic number.

2215891 is a deficient number, since it is larger than the sum of its proper divisors (33141).

2215891 is an equidigital number, since it uses as much as digits as its factorization.

2215891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33140.

The product of its digits is 1440, while the sum is 28.

The square root of 2215891 is about 1488.5869138213. The cubic root of 2215891 is about 130.3715406735.

The spelling of 2215891 in words is "two million, two hundred fifteen thousand, eight hundred ninety-one".