20202121221 has 4 divisors (see below), whose sum is σ = 26936161632. Its totient is φ = 13468080812.

The previous prime is 20202121217. The next prime is 20202121229. The reversal of 20202121221 is 12212120202.

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 20202121221 - 2² = 20202121217 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20202121221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20202121229) 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, 3367020201 + ... + 3367020206.

It is an arithmetic number, because the mean of its divisors is an integer number (6734040408).

Almost surely, 2^20202121221 is an apocalyptic number.

It is an amenable number.

20202121221 is a deficient number, since it is larger than the sum of its proper divisors (6734040411).

20202121221 is an equidigital number, since it uses as much as digits as its factorization.

20202121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6734040410.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 20202121221 its reverse (12212120202), we get a palindrome (32414241423).

The spelling of 20202121221 in words is "twenty billion, two hundred two million, one hundred twenty-one thousand, two hundred twenty-one".