21012100200021 has 128 divisors (see below), whose sum is σ = 34013693952000. Its totient is φ = 11524397713920.

The previous prime is 21012100199941. The next prime is 21012100200031. The reversal of 21012100200021 is 12000200121012.

It is not a de Polignac number, because 21012100200021 - 2¹⁰ = 21012100198997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012100200031) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 943208335 + ... + 943230611.

It is an arithmetic number, because the mean of its divisors is an integer number (265731984000).

Almost surely, 2^{21012100200021} is an apocalyptic number.

21012100200021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21012100200021 is a deficient number, since it is larger than the sum of its proper divisors (13001593751979).

21012100200021 is a wasteful number, since it uses less digits than its factorization.

21012100200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22704 (or 22690 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21012100200021 its reverse (12000200121012), we get a palindrome (33012300321033).

The spelling of 21012100200021 in words is "twenty-one trillion, twelve billion, one hundred million, two hundred thousand, twenty-one".