21121111211200 has 672 divisors, whose sum is σ = 69877277568000. Its totient is φ = 6068282572800.

The previous prime is 21121111211107. The next prime is 21121111211203. The reversal of 21121111211200 is 211211112112.

It is a super-2 number, since 2×21121111211200² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (21121111211203) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1189979926 + ... + 1189997674.

It is an arithmetic number, because the mean of its divisors is an integer number (103984044000).

Almost surely, 2^{21121111211200} is an apocalyptic number.

21121111211200 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 21121111211200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34938638784000).

21121111211200 is an abundant number, since it is smaller than the sum of its proper divisors (48756166356800).

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

21121111211200 is a wasteful number, since it uses less digits than its factorization.

21121111211200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18545 (or 18530 counting only the distinct ones).

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

Adding to 21121111211200 its reverse (211211112112), we get a palindrome (21332322323312).

21121111211200 divided by its reverse (211211112112) gives a square (100 = 10²).

It can be divided in two parts, 211211 and 11211200, that added together give a palindrome (11422411).

The spelling of 21121111211200 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, two hundred eleven thousand, two hundred".