21211211111200 has 576 divisors, whose sum is σ = 60133183729920. Its totient is φ = 7233873920000.

The previous prime is 21211211111197. The next prime is 21211211111231. The reversal of 21211211111200 is 211111211212.

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

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1366077837 + ... + 1366093363.

It is an arithmetic number, because the mean of its divisors is an integer number (104397888420).

Almost surely, 2^{21211211111200} is an apocalyptic number.

21211211111200 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 21211211111200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30066591864960).

21211211111200 is an abundant number, since it is smaller than the sum of its proper divisors (38921972618720).

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

21211211111200 is a wasteful number, since it uses less digits than its factorization.

21211211111200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15741 (or 15728 counting only the distinct ones).

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

Adding to 21211211111200 its reverse (211111211212), we get a palindrome (21422322322412).

The spelling of 21211211111200 in words is "twenty-one trillion, two hundred eleven billion, two hundred eleven million, one hundred eleven thousand, two hundred".