1221212100100 has 18 divisors (see below), whose sum is σ = 2650030257434. Its totient is φ = 488484840000.

The previous prime is 1221212100077. The next prime is 1221212100107. The reversal of 1221212100100 is 10012121221.

It can be written as a sum of positive squares in 3 ways, for example, as 189447785536 + 1031764314564 = 435256^2 + 1015758^2 .

It is not an unprimeable number, because it can be changed into a prime (1221212100107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6106060401 + ... + 6106060600.

Almost surely, 2^{1221212100100} is an apocalyptic number.

1221212100100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221212100100 is an abundant number, since it is smaller than the sum of its proper divisors (1428818157334).

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

1221212100100 is a wasteful number, since it uses less digits than its factorization.

1221212100100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12212121015 (or 12212121008 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 1221212100100 its reverse (10012121221), we get a palindrome (1231224221321).

The spelling of 1221212100100 in words is "one trillion, two hundred twenty-one billion, two hundred twelve million, one hundred thousand, one hundred".