212121212210221 has 16 divisors (see below), whose sum is σ = 218513306803824. Its totient is φ = 205850371313664.

The previous prime is 212121212210209. The next prime is 212121212210231. The reversal of 212121212210221 is 122012212121212.

It can be written as a sum of positive squares in 8 ways, for example, as 18290496474121 + 193830715736100 = 4276739^2 + 13922310^2 .

It is a cyclic number.

It is not a de Polignac number, because 212121212210221 - 2⁴⁵ = 176936840121389 is a prime.

It is a super-2 number, since 2×212121212210221² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212121212210192 and 212121212210201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212121212210231) 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 15 ways as a sum of consecutive naturals, for example, 92719446 + ... + 94979671.

It is an arithmetic number, because the mean of its divisors is an integer number (13657081675239).

Almost surely, 2^{212121212210221} is an apocalyptic number.

It is an amenable number.

212121212210221 is a deficient number, since it is larger than the sum of its proper divisors (6392094593603).

212121212210221 is a wasteful number, since it uses less digits than its factorization.

212121212210221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187699440.

The product of its (nonzero) digits is 256, while the sum is 22.

Adding to 212121212210221 its reverse (122012212121212), we get a palindrome (334133424331433).

The spelling of 212121212210221 in words is "two hundred twelve trillion, one hundred twenty-one billion, two hundred twelve million, two hundred ten thousand, two hundred twenty-one".