2021221100021 has 4 divisors (see below), whose sum is σ = 2026261552044. Its totient is φ = 2016180648000.

The previous prime is 2021221099993. The next prime is 2021221100029. The reversal of 2021221100021 is 1200011221202.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1063981935025 + 957239164996 = 1031495^2 + 978386^2 .

It is a cyclic number.

It is not a de Polignac number, because 2021221100021 - 2¹⁰ = 2021221098997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2021221099969 and 2021221100005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021221100029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2520225410 + ... + 2520226211.

It is an arithmetic number, because the mean of its divisors is an integer number (506565388011).

Almost surely, 2^{2021221100021} is an apocalyptic number.

It is an amenable number.

2021221100021 is a deficient number, since it is larger than the sum of its proper divisors (5040452023).

2021221100021 is an equidigital number, since it uses as much as digits as its factorization.

2021221100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5040452022.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 2021221100021 its reverse (1200011221202), we get a palindrome (3221232321223).

The spelling of 2021221100021 in words is "two trillion, twenty-one billion, two hundred twenty-one million, one hundred thousand, twenty-one".