212121011221 has 24 divisors (see below), whose sum is σ = 251430036504. Its totient is φ = 178397614080.

The previous prime is 212121011171. The next prime is 212121011227. The reversal of 212121011221 is 122110121212.

It can be written as a sum of positive squares in 4 ways, for example, as 59689330596 + 152431680625 = 244314^2 + 390425^2 .

It is not a de Polignac number, because 212121011221 - 2⁷ = 212121011093 is a prime.

It is a super-3 number, since 3×212121011221³ (a number of 35 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212121011195 and 212121011204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212121011227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 536731 + ... + 843991.

It is an arithmetic number, because the mean of its divisors is an integer number (10476251521).

Almost surely, 2^212121011221 is an apocalyptic number.

It is an amenable number.

212121011221 is a deficient number, since it is larger than the sum of its proper divisors (39309025283).

212121011221 is a wasteful number, since it uses less digits than its factorization.

212121011221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307541 (or 307534 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 212121011221 its reverse (122110121212), we get a palindrome (334231132433).

The spelling of 212121011221 in words is "two hundred twelve billion, one hundred twenty-one million, eleven thousand, two hundred twenty-one".