21111210121200 has 480 divisors, whose sum is σ = 70968264734400. Its totient is φ = 5357571932160.

The previous prime is 21111210121181. The next prime is 21111210121217. The reversal of 21111210121200 is 212101211112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21111210121200.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 732073182 + ... + 732102018.

It is an arithmetic number, because the mean of its divisors is an integer number (147850551530).

Almost surely, 2^{21111210121200} is an apocalyptic number.

21111210121200 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 21111210121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35484132367200).

21111210121200 is an abundant number, since it is smaller than the sum of its proper divisors (49857054613200).

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

21111210121200 is a wasteful number, since it uses less digits than its factorization.

21111210121200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29189 (or 29178 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21111210121200 its reverse (212101211112), we get a palindrome (21323311332312).

The spelling of 21111210121200 in words is "twenty-one trillion, one hundred eleven billion, two hundred ten million, one hundred twenty-one thousand, two hundred".