21100101100020 has 72 divisors (see below), whose sum is σ = 64004373809376. Its totient is φ = 5626629116352.

The previous prime is 21100101100009. The next prime is 21100101100037. The reversal of 21100101100020 is 2000110100112.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21100101099975 and 21100101100011.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16252239 + ... + 17502441.

Almost surely, 2^{21100101100020} is an apocalyptic number.

21100101100020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100101100020 is an abundant number, since it is smaller than the sum of its proper divisors (42904272709356).

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

21100101100020 is a wasteful number, since it uses less digits than its factorization.

21100101100020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343981 (or 1343976 counting only the distinct ones).

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

Adding to 21100101100020 its reverse (2000110100112), we get a palindrome (23100211200132).

The spelling of 21100101100020 in words is "twenty-one trillion, one hundred billion, one hundred one million, one hundred thousand, twenty".