21011220221200 has 180 divisors, whose sum is σ = 56378965519728. Its totient is φ = 7462756089600.

The previous prime is 21011220221099. The next prime is 21011220221239. The reversal of 21011220221200 is 212202211012.

It is a happy number.

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

It is an unprimeable number.

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, 6844287 + ... + 9426913.

Almost surely, 2^{21011220221200} is an apocalyptic number.

21011220221200 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 21011220221200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28189482759864).

21011220221200 is an abundant number, since it is smaller than the sum of its proper divisors (35367745298528).

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

21011220221200 is a wasteful number, since it uses less digits than its factorization.

21011220221200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2582742 (or 2582688 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21011220221200 its reverse (212202211012), we get a palindrome (21223422432212).

The spelling of 21011220221200 in words is "twenty-one trillion, eleven billion, two hundred twenty million, two hundred twenty-one thousand, two hundred".