20211221001 has 32 divisors (see below), whose sum is σ = 29608574976. Its totient is φ = 12208032000.

The previous prime is 20211220973. The next prime is 20211221033. The reversal of 20211221001 is 10012211202.

It is not a de Polignac number, because 20211221001 - 2²⁷ = 20077003273 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20211271001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 268506 + ... + 335436.

It is an arithmetic number, because the mean of its divisors is an integer number (925267968).

Almost surely, 2^20211221001 is an apocalyptic number.

It is an amenable number.

20211221001 is a deficient number, since it is larger than the sum of its proper divisors (9397353975).

20211221001 is a wasteful number, since it uses less digits than its factorization.

20211221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67173.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 20211221001 its reverse (10012211202), we get a palindrome (30223432203).

The spelling of 20211221001 in words is "twenty billion, two hundred eleven million, two hundred twenty-one thousand, one".