20021212021 has 4 divisors (see below), whose sum is σ = 20064642444. Its totient is φ = 19977781600.

The previous prime is 20021212007. The next prime is 20021212031. The reversal of 20021212021 is 12021212002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12021212002 = 2 ⋅6010606001.

It can be written as a sum of positive squares in 2 ways, for example, as 6498778225 + 13522433796 = 80615^2 + 116286^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021212021 - 2⁵ = 20021211989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021211992 and 20021212010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021212031) 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, 21714520 + ... + 21715441.

It is an arithmetic number, because the mean of its divisors is an integer number (5016160611).

Almost surely, 2^20021212021 is an apocalyptic number.

It is an amenable number.

20021212021 is a deficient number, since it is larger than the sum of its proper divisors (43430423).

20021212021 is an equidigital number, since it uses as much as digits as its factorization.

20021212021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43430422.

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

Adding to 20021212021 its reverse (12021212002), we get a palindrome (32042424023).

The spelling of 20021212021 in words is "twenty billion, twenty-one million, two hundred twelve thousand, twenty-one".