1221100100000 has 576 divisors, whose sum is σ = 3433673980800. Its totient is φ = 423360000000.

The previous prime is 1221100099997. The next prime is 1221100100021. The reversal of 1221100100000 is 10011221.

It is a Harshad number since it is a multiple of its sum of digits (8).

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, 3221899811 + ... + 3221900189.

It is an arithmetic number, because the mean of its divisors is an integer number (5961239550).

Almost surely, 2^{1221100100000} is an apocalyptic number.

1221100100000 is a gapful number since it is divisible by the number (10) 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 1221100100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1716836990400).

1221100100000 is an abundant number, since it is smaller than the sum of its proper divisors (2212573880800).

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

1221100100000 is a wasteful number, since it uses less digits than its factorization.

1221100100000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555 (or 527 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 1221100100000 its reverse (10011221), we get a palindrome (1221110111221).

The spelling of 1221100100000 in words is "one trillion, two hundred twenty-one billion, one hundred million, one hundred thousand".