21202331221 has 4 divisors (see below), whose sum is σ = 21203426700. Its totient is φ = 21201235744.

The previous prime is 21202331219. The next prime is 21202331231. The reversal of 21202331221 is 12213320212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17889062500 + 3313268721 = 133750^2 + 57561^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202331221 - 2¹ = 21202331219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202331231) 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, 518176 + ... + 557593.

It is an arithmetic number, because the mean of its divisors is an integer number (5300856675).

Almost surely, 2^21202331221 is an apocalyptic number.

It is an amenable number.

21202331221 is a deficient number, since it is larger than the sum of its proper divisors (1095479).

21202331221 is a wasteful number, since it uses less digits than its factorization.

21202331221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095478.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21202331221 its reverse (12213320212), we get a palindrome (33415651433).

The spelling of 21202331221 in words is "twenty-one billion, two hundred two million, three hundred thirty-one thousand, two hundred twenty-one".