21101221211100 has 144 divisors (see below), whose sum is σ = 61229602408800. Its totient is φ = 5610715729920.

The previous prime is 21101221211093. The next prime is 21101221211117. The reversal of 21101221211100 is 111212210112.

It is a happy number.

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 21101221211100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 281804466 + ... + 281879334.

Almost surely, 2^{21101221211100} is an apocalyptic number.

21101221211100 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 21101221211100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30614801204400).

21101221211100 is an abundant number, since it is smaller than the sum of its proper divisors (40128381197700).

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

21101221211100 is a wasteful number, since it uses less digits than its factorization.

21101221211100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77592 (or 77585 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21101221211100 its reverse (111212210112), we get a palindrome (21212433421212).

The spelling of 21101221211100 in words is "twenty-one trillion, one hundred one billion, two hundred twenty-one million, two hundred eleven thousand, one hundred".