2191021 has 4 divisors (see below), whose sum is σ = 2504032. Its totient is φ = 1878012.

The previous prime is 2191019. The next prime is 2191027. The reversal of 2191021 is 1201912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2191021 - 2¹ = 2191019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2190986 and 2191004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2191027) 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, 156495 + ... + 156508.

It is an arithmetic number, because the mean of its divisors is an integer number (626008).

2^2191021 is an apocalyptic number.

It is an amenable number.

2191021 is a deficient number, since it is larger than the sum of its proper divisors (313011).

2191021 is an equidigital number, since it uses as much as digits as its factorization.

2191021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313010.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 2191021 is about 1480.2097824295. The cubic root of 2191021 is about 129.8819638651.

Adding to 2191021 its reverse (1201912), we get a palindrome (3392933).

The spelling of 2191021 in words is "two million, one hundred ninety-one thousand, twenty-one".