1221100212222 has 192 divisors, whose sum is σ = 3066441041664. Its totient is φ = 360988669440.

The previous prime is 1221100212209. The next prime is 1221100212257. The reversal of 1221100212222 is 2222120011221.

It is a happy number.

1221100212222 is a `hidden beast` number, since 1 + 221 + 10 + 0 + 212 + 222 = 666.

It is a super-2 number, since 2×1221100212222² (a number of 25 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 1221100212195 and 1221100212204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 224588088 + ... + 224593524.

It is an arithmetic number, because the mean of its divisors is an integer number (15971047092).

Almost surely, 2^{1221100212222} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221100212222, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1533220520832).

1221100212222 is an abundant number, since it is smaller than the sum of its proper divisors (1845340829442).

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

1221100212222 is a wasteful number, since it uses less digits than its factorization.

1221100212222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6485 (or 6473 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 1221100212222 its reverse (2222120011221), we get a palindrome (3443220223443).

The spelling of 1221100212222 in words is "one trillion, two hundred twenty-one billion, one hundred million, two hundred twelve thousand, two hundred twenty-two".