221221222100 has 72 divisors (see below), whose sum is σ = 488216127168. Its totient is φ = 86991148800.

The previous prime is 221221222091. The next prime is 221221222147. The reversal of 221221222100 is 1222122122.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2191745 + ... + 2290455.

It is an arithmetic number, because the mean of its divisors is an integer number (6780779544).

Almost surely, 2^221221222100 is an apocalyptic number.

221221222100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221221222100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (244108063584).

221221222100 is an abundant number, since it is smaller than the sum of its proper divisors (266994905068).

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

221221222100 is a wasteful number, since it uses less digits than its factorization.

221221222100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99105 (or 99098 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 221221222100 its reverse (1222122122), we get a palindrome (222443344222).

The spelling of 221221222100 in words is "two hundred twenty-one billion, two hundred twenty-one million, two hundred twenty-two thousand, one hundred".