221212212221 has 48 divisors (see below), whose sum is σ = 303362879232. Its totient is φ = 156933469440.

The previous prime is 221212212161. The next prime is 221212212253. The reversal of 221212212221 is 122212212122.

It is not a de Polignac number, because 221212212221 - 2¹⁸ = 221211950077 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221212212193 and 221212212202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221212212121) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 666200 + ... + 941406.

It is an arithmetic number, because the mean of its divisors is an integer number (6320059984).

Almost surely, 2^221212212221 is an apocalyptic number.

It is an amenable number.

221212212221 is a deficient number, since it is larger than the sum of its proper divisors (82150667011).

221212212221 is a wasteful number, since it uses less digits than its factorization.

221212212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275322 (or 275311 counting only the distinct ones).

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

Adding to 221212212221 its reverse (122212212122), we get a palindrome (343424424343).

Subtracting from 221212212221 its reverse (122212212122), we obtain a palindrome (99000000099).

The spelling of 221212212221 in words is "two hundred twenty-one billion, two hundred twelve million, two hundred twelve thousand, two hundred twenty-one".