20212100021 has 4 divisors (see below), whose sum is σ = 20212422252. Its totient is φ = 20211777792.

The previous prime is 20212099979. The next prime is 20212100039. The reversal of 20212100021 is 12000121202.

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: 12000121202 = 2 ⋅6000060601.

It can be written as a sum of positive squares in 2 ways, for example, as 16212928900 + 3999171121 = 127330^2 + 63239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20212100021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20212099975 and 20212100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20212160021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33146 + ... + 203771.

It is an arithmetic number, because the mean of its divisors is an integer number (5053105563).

Almost surely, 2^20212100021 is an apocalyptic number.

It is an amenable number.

20212100021 is a deficient number, since it is larger than the sum of its proper divisors (322231).

20212100021 is an equidigital number, since it uses as much as digits as its factorization.

20212100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322230.

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

Adding to 20212100021 its reverse (12000121202), we get a palindrome (32212221223).

The spelling of 20212100021 in words is "twenty billion, two hundred twelve million, one hundred thousand, twenty-one".