20021021221 has 4 divisors (see below), whose sum is σ = 21074759200. Its totient is φ = 18967283244.

The previous prime is 20021021203. The next prime is 20021021249. The reversal of 20021021221 is 12212012002.

It is a happy number.

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 20021021221 - 2⁷ = 20021021093 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 (20021021021) 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, 526868961 + ... + 526868998.

It is an arithmetic number, because the mean of its divisors is an integer number (5268689800).

Almost surely, 2^20021021221 is an apocalyptic number.

It is an amenable number.

20021021221 is a deficient number, since it is larger than the sum of its proper divisors (1053737979).

20021021221 is a wasteful number, since it uses less digits than its factorization.

20021021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053737978.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 20021021221 its reverse (12212012002), we get a palindrome (32233033223).

The spelling of 20021021221 in words is "twenty billion, twenty-one million, twenty-one thousand, two hundred twenty-one".