20211220011221 has 4 divisors (see below), whose sum is σ = 20224085206944. Its totient is φ = 20198354815500.

The previous prime is 20211220011187. The next prime is 20211220011317. The reversal of 20211220011221 is 12211002211202.

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-20211220011221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20211220011221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20211220011121) 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, 6432595505 + ... + 6432598646.

It is an arithmetic number, because the mean of its divisors is an integer number (5056021301736).

Almost surely, 2^{20211220011221} is an apocalyptic number.

It is an amenable number.

20211220011221 is a deficient number, since it is larger than the sum of its proper divisors (12865195723).

20211220011221 is a wasteful number, since it uses less digits than its factorization.

20211220011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12865195722.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 20211220011221 its reverse (12211002211202), we get a palindrome (32422222222423).

The spelling of 20211220011221 in words is "twenty trillion, two hundred eleven billion, two hundred twenty million, eleven thousand, two hundred twenty-one".