20121221100 has 72 divisors (see below), whose sum is σ = 60748611840. Its totient is φ = 5132367680.

The previous prime is 20121221041. The next prime is 20121221117. The reversal of 20121221100 is 112212102.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1451160 + ... + 1464959.

It is an arithmetic number, because the mean of its divisors is an integer number (843730720).

Almost surely, 2^20121221100 is an apocalyptic number.

20121221100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20121221100 is an abundant number, since it is smaller than the sum of its proper divisors (40627390740).

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

20121221100 is a wasteful number, since it uses less digits than its factorization.

20121221100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2916159 (or 2916152 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 20121221100 its reverse (112212102), we get a palindrome (20233433202).

The spelling of 20121221100 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred".