21100121200 has 180 divisors, whose sum is σ = 54107951800. Its totient is φ = 7905669120.

The previous prime is 21100121117. The next prime is 21100121213. The reversal of 21100121200 is 212100112.

It is a super-2 number, since 2×21100121200² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 40344139 + ... + 40344661.

Almost surely, 2^21100121200 is an apocalyptic number.

21100121200 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 21100121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27053975900).

21100121200 is an abundant number, since it is smaller than the sum of its proper divisors (33007830600).

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

21100121200 is a wasteful number, since it uses less digits than its factorization.

21100121200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 924 (or 896 counting only the distinct ones).

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

Adding to 21100121200 its reverse (212100112), we get a palindrome (21312221312).

The spelling of 21100121200 in words is "twenty-one billion, one hundred million, one hundred twenty-one thousand, two hundred".