20211220221 has 8 divisors (see below), whose sum is σ = 27020542560. Its totient is φ = 13438022352.

The previous prime is 20211220213. The next prime is 20211220247. The reversal of 20211220221 is 12202211202.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20211220221 - 2³ = 20211220213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20211220221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20211221221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9029811 + ... + 9032048.

It is an arithmetic number, because the mean of its divisors is an integer number (3377567820).

Almost surely, 2^20211220221 is an apocalyptic number.

It is an amenable number.

20211220221 is a deficient number, since it is larger than the sum of its proper divisors (6809322339).

20211220221 is a wasteful number, since it uses less digits than its factorization.

20211220221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18062235.

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

Adding to 20211220221 its reverse (12202211202), we get a palindrome (32413431423).

The spelling of 20211220221 in words is "twenty billion, two hundred eleven million, two hundred twenty thousand, two hundred twenty-one".