221221111212 has 36 divisors (see below), whose sum is σ = 559495583920. Its totient is φ = 73701103392.

The previous prime is 221221111123. The next prime is 221221111217. The reversal of 221221111212 is 212111122122.

221221111212 is a `hidden beast` number, since 221 + 221 + 1 + 11 + 212 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (221221111217) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1567543 + ... + 1702830.

Almost surely, 2^221221111212 is an apocalyptic number.

It is an amenable number.

221221111212 is an abundant number, since it is smaller than the sum of its proper divisors (338274472708).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221221111212 is a wasteful number, since it uses less digits than its factorization.

221221111212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3272262 (or 3272257 counting only the distinct ones).

The product of its digits is 64, while the sum is 18.

Adding to 221221111212 its reverse (212111122122), we get a palindrome (433332233334).

The spelling of 221221111212 in words is "two hundred twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, two hundred twelve".