21011021221200 has 120 divisors (see below), whose sum is σ = 67327390920000. Its totient is φ = 5601100385280.

The previous prime is 21011021221189. The next prime is 21011021221217. The reversal of 21011021221200 is 212212011012.

It is a tau number, because it is divible by the number of its divisors (120).

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 21011021221200.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 787501 + ... + 6530099.

It is an arithmetic number, because the mean of its divisors is an integer number (561061591000).

Almost surely, 2^{21011021221200} is an apocalyptic number.

21011021221200 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 21011021221200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33663695460000).

21011021221200 is an abundant number, since it is smaller than the sum of its proper divisors (46316369698800).

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

21011021221200 is a wasteful number, since it uses less digits than its factorization.

21011021221200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5745669 (or 5745658 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21011021221200 its reverse (212212011012), we get a palindrome (21223233232212).

The spelling of 21011021221200 in words is "twenty-one trillion, eleven billion, twenty-one million, two hundred twenty-one thousand, two hundred".