21220203221 has 4 divisors (see below), whose sum is σ = 24251660832. Its totient is φ = 18188745612.

The previous prime is 21220203211. The next prime is 21220203271. The reversal of 21220203221 is 12230202212.

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-21220203221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21220203221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220203211) 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, 1515728795 + ... + 1515728808.

It is an arithmetic number, because the mean of its divisors is an integer number (6062915208).

Almost surely, 2^21220203221 is an apocalyptic number.

It is an amenable number.

21220203221 is a deficient number, since it is larger than the sum of its proper divisors (3031457611).

21220203221 is an equidigital number, since it uses as much as digits as its factorization.

21220203221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3031457610.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21220203221 its reverse (12230202212), we get a palindrome (33450405433).

The spelling of 21220203221 in words is "twenty-one billion, two hundred twenty million, two hundred three thousand, two hundred twenty-one".