20021111221 has 4 divisors (see below), whose sum is σ = 20021439744. Its totient is φ = 20020782700.

The previous prime is 20021111161. The next prime is 20021111239. The reversal of 20021111221 is 12211112002.

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 20021111221 - 2²¹ = 20019014069 is a prime.

It is a super-2 number, since 2×20021111221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021111251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43015 + ... + 204676.

It is an arithmetic number, because the mean of its divisors is an integer number (5005359936).

Almost surely, 2^20021111221 is an apocalyptic number.

It is an amenable number.

20021111221 is a deficient number, since it is larger than the sum of its proper divisors (328523).

20021111221 is an equidigital number, since it uses as much as digits as its factorization.

20021111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328522.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 20021111221 its reverse (12211112002), we get a palindrome (32232223223).

The spelling of 20021111221 in words is "twenty billion, twenty-one million, one hundred eleven thousand, two hundred twenty-one".