2121204221 has 4 divisors (see below), whose sum is σ = 2122939872. Its totient is φ = 2119468572.

The previous prime is 2121204203. The next prime is 2121204227. The reversal of 2121204221 is 1224021212.

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 a de Polignac number, because none of the positive numbers 2^k-2121204221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2121204221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121204227) 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, 865991 + ... + 868436.

It is an arithmetic number, because the mean of its divisors is an integer number (530734968).

Almost surely, 2^2121204221 is an apocalyptic number.

It is an amenable number.

2121204221 is a deficient number, since it is larger than the sum of its proper divisors (1735651).

2121204221 is a wasteful number, since it uses less digits than its factorization.

2121204221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735650.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 2121204221 is about 46056.5328807977. The cubic root of 2121204221 is about 1284.8748475870.

Adding to 2121204221 its reverse (1224021212), we get a palindrome (3345225433).

The spelling of 2121204221 in words is "two billion, one hundred twenty-one million, two hundred four thousand, two hundred twenty-one".