20121021100 has 18 divisors (see below), whose sum is σ = 43662616004. Its totient is φ = 8048408400.

The previous prime is 20121021083. The next prime is 20121021101. The reversal of 20121021100 is 112012102.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (20121021101) 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, 100605006 + ... + 100605205.

Almost surely, 2^20121021100 is an apocalyptic number.

20121021100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20121021100 is an abundant number, since it is smaller than the sum of its proper divisors (23541594904).

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

20121021100 is a wasteful number, since it uses less digits than its factorization.

20121021100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201210225 (or 201210218 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 20121021100 its reverse (112012102), we get a palindrome (20233033202).

The spelling of 20121021100 in words is "twenty billion, one hundred twenty-one million, twenty-one thousand, one hundred".