212121220020221 has 4 divisors (see below), whose sum is σ = 213544852369500. Its totient is φ = 210697587670944.

The previous prime is 212121220020217. The next prime is 212121220020251. The reversal of 212121220020221 is 122020022121212.

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 37113852988996 + 175007367031225 = 6092114^2 + 13229035^2 .

It is a cyclic number.

It is not a de Polignac number, because 212121220020221 - 2² = 212121220020217 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212121220020193 and 212121220020202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212121220020251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 711816174416 + ... + 711816174713.

It is an arithmetic number, because the mean of its divisors is an integer number (53386213092375).

Almost surely, 2^{212121220020221} is an apocalyptic number.

It is an amenable number.

212121220020221 is a deficient number, since it is larger than the sum of its proper divisors (1423632349279).

212121220020221 is a wasteful number, since it uses less digits than its factorization.

212121220020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1423632349278.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 212121220020221 its reverse (122020022121212), we get a palindrome (334141242141433).

The spelling of 212121220020221 in words is "two hundred twelve trillion, one hundred twenty-one billion, two hundred twenty million, twenty thousand, two hundred twenty-one".