21101200021 has 16 divisors (see below), whose sum is σ = 23188032000. Its totient is φ = 19042831600.

The previous prime is 21101200007. The next prime is 21101200033. The reversal of 21101200021 is 12000210112.

It is a cyclic number.

It is not a de Polignac number, because 21101200021 - 2⁷ = 21101199893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101199980 and 21101200007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101200051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1170486 + ... + 1188376.

It is an arithmetic number, because the mean of its divisors is an integer number (1449252000).

Almost surely, 2^21101200021 is an apocalyptic number.

It is an amenable number.

21101200021 is a deficient number, since it is larger than the sum of its proper divisors (2086831979).

21101200021 is a wasteful number, since it uses less digits than its factorization.

21101200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18680.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21101200021 its reverse (12000210112), we get a palindrome (33101410133).

It can be divided in two parts, 21101 and 200021, that added together give a palindrome (221122).

The spelling of 21101200021 in words is "twenty-one billion, one hundred one million, two hundred thousand, twenty-one".