20121200100 has 108 divisors (see below), whose sum is σ = 63777675780. Its totient is φ = 5305344000.

The previous prime is 20121200087. The next prime is 20121200107. The reversal of 20121200100 is 100212102.

It can be written as a sum of positive squares in 6 ways, for example, as 2032026084 + 18089174016 = 45078^2 + 134496^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (20121200107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 45501 + ... + 205700.

It is an arithmetic number, because the mean of its divisors is an integer number (590534035).

Almost surely, 2^20121200100 is an apocalyptic number.

20121200100 is a gapful number since it is divisible by the number (20) 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 20121200100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31888837890).

20121200100 is an abundant number, since it is smaller than the sum of its proper divisors (43656475680).

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

20121200100 is a wasteful number, since it uses less digits than its factorization.

20121200100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251310 (or 251300 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 20121200100 its reverse (100212102), we get a palindrome (20221412202).

The spelling of 20121200100 in words is "twenty billion, one hundred twenty-one million, two hundred thousand, one hundred".