20211221111021 has 4 divisors (see below), whose sum is σ = 20291743904544. Its totient is φ = 20130698317500.

The previous prime is 20211221110987. The next prime is 20211221111047. The reversal of 20211221111021 is 12011112211202.

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 20211221111021 - 2⁴² = 15813174599917 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 (20211221101021) 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, 40261396385 + ... + 40261396886.

It is an arithmetic number, because the mean of its divisors is an integer number (5072935976136).

Almost surely, 2^{20211221111021} is an apocalyptic number.

It is an amenable number.

20211221111021 is a deficient number, since it is larger than the sum of its proper divisors (80522793523).

20211221111021 is an equidigital number, since it uses as much as digits as its factorization.

20211221111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80522793522.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 20211221111021 its reverse (12011112211202), we get a palindrome (32222333322223).

The spelling of 20211221111021 in words is "twenty trillion, two hundred eleven billion, two hundred twenty-one million, one hundred eleven thousand, twenty-one".