1221210121110 has 256 divisors, whose sum is σ = 3460881973248. Its totient is φ = 269988940800.

The previous prime is 1221210121097. The next prime is 1221210121139. The reversal of 1221210121110 is 111210121221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 1221210121110.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 520326957 + ... + 520329303.

It is an arithmetic number, because the mean of its divisors is an integer number (13519070208).

Almost surely, 2^{1221210121110} is an apocalyptic number.

1221210121110 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221210121110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1730440986624).

1221210121110 is an abundant number, since it is smaller than the sum of its proper divisors (2239671852138).

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

1221210121110 is a wasteful number, since it uses less digits than its factorization.

1221210121110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2899.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 1221210121110 its reverse (111210121221), we get a palindrome (1332420242331).

The spelling of 1221210121110 in words is "one trillion, two hundred twenty-one billion, two hundred ten million, one hundred twenty-one thousand, one hundred ten".