2161221 has 4 divisors (see below), whose sum is σ = 2881632. Its totient is φ = 1440812.

The previous prime is 2161213. The next prime is 2161253. The reversal of 2161221 is 1221612.

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 2161221 - 2³ = 2161213 is a prime.

It is a D-number.

It is a self number, because there is not a number n which added to its sum of digits gives 2161221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161121) 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, 360201 + ... + 360206.

It is an arithmetic number, because the mean of its divisors is an integer number (720408).

2^2161221 is an apocalyptic number.

It is an amenable number.

2161221 is a deficient number, since it is larger than the sum of its proper divisors (720411).

2161221 is an equidigital number, since it uses as much as digits as its factorization.

2161221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 720410.

The product of its digits is 48, while the sum is 15.

The square root of 2161221 is about 1470.1091796190. The cubic root of 2161221 is about 129.2904338949.

Adding to 2161221 its reverse (1221612), we get a palindrome (3382833).

The spelling of 2161221 in words is "two million, one hundred sixty-one thousand, two hundred twenty-one".