21011220212100 has 72 divisors (see below), whose sum is σ = 62888755695360. Its totient is φ = 5409785431680.

The previous prime is 21011220212089. The next prime is 21011220212107. The reversal of 21011220212100 is 121202211012.

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 21011220212100.

It is not an unprimeable number, because it can be changed into a prime (21011220212107) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 1207532692 + ... + 1207550091.

Almost surely, 2^{21011220212100} is an apocalyptic number.

21011220212100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011220212100 is an abundant number, since it is smaller than the sum of its proper divisors (41877535483260).

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

21011220212100 is a wasteful number, since it uses less digits than its factorization.

21011220212100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2415082829 (or 2415082822 counting only the distinct ones).

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

Adding to 21011220212100 its reverse (121202211012), we get a palindrome (21132422423112).

The spelling of 21011220212100 in words is "twenty-one trillion, eleven billion, two hundred twenty million, two hundred twelve thousand, one hundred".