21001101001200 has 240 divisors, whose sum is σ = 74753184760800. Its totient is φ = 5599932364800.

The previous prime is 21001101001151. The next prime is 21001101001201. The reversal of 21001101001200 is 210010110012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001101001201) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 195653146 + ... + 195760454.

It is an arithmetic number, because the mean of its divisors is an integer number (311471603170).

Almost surely, 2^{21001101001200} is an apocalyptic number.

21001101001200 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 21001101001200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37376592380400).

21001101001200 is an abundant number, since it is smaller than the sum of its proper divisors (53752083759600).

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

21001101001200 is a wasteful number, since it uses less digits than its factorization.

21001101001200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125457 (or 125440 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21001101001200 its reverse (210010110012), we get a palindrome (21211111111212).

The spelling of 21001101001200 in words is "twenty-one trillion, one billion, one hundred one million, one thousand, two hundred".