1221100222212 has 288 divisors, whose sum is σ = 3809909779200. Its totient is φ = 335007747072.

The previous prime is 1221100222211. The next prime is 1221100222247. The reversal of 1221100222212 is 2122220011221.

It is a happy number.

1221100222212 is a `hidden beast` number, since 1 + 221 + 10 + 0 + 222 + 212 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (1221100222211) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 8545489 + ... + 8687207.

It is an arithmetic number, because the mean of its divisors is an integer number (13228853400).

Almost surely, 2^{1221100222212} is an apocalyptic number.

1221100222212 is a gapful number since it is divisible by the number (12) 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 1221100222212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1904954889600).

1221100222212 is an abundant number, since it is smaller than the sum of its proper divisors (2588809556988).

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

1221100222212 is a wasteful number, since it uses less digits than its factorization.

1221100222212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141800 (or 141773 counting only the distinct ones).

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

Adding to 1221100222212 its reverse (2122220011221), we get a palindrome (3343320233433).

The spelling of 1221100222212 in words is "one trillion, two hundred twenty-one billion, one hundred million, two hundred twenty-two thousand, two hundred twelve".