20201221001 has 16 divisors (see below), whose sum is σ = 21882283584. Its totient is φ = 18538559424.

The previous prime is 20201220961. The next prime is 20201221003. The reversal of 20201221001 is 10012210202.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20201221001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20201221003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2229386 + ... + 2238428.

It is an arithmetic number, because the mean of its divisors is an integer number (1367642724).

Almost surely, 2^20201221001 is an apocalyptic number.

It is an amenable number.

20201221001 is a deficient number, since it is larger than the sum of its proper divisors (1681062583).

20201221001 is a wasteful number, since it uses less digits than its factorization.

20201221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10040.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 20201221001 its reverse (10012210202), we get a palindrome (30213431203).

The spelling of 20201221001 in words is "twenty billion, two hundred one million, two hundred twenty-one thousand, one".