21000200021021 has 16 divisors (see below), whose sum is σ = 23603637872640. Its totient is φ = 18538249783680.

The previous prime is 21000200020981. The next prime is 21000200021029. The reversal of 21000200021021 is 12012000200012.

It is a happy number.

It is not a de Polignac number, because 21000200021021 - 2¹⁸ = 21000199758877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000200020993 and 21000200021011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000200021029) 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, 5581565 + ... + 8553026.

It is an arithmetic number, because the mean of its divisors is an integer number (1475227367040).

Almost surely, 2^{21000200021021} is an apocalyptic number.

It is an amenable number.

21000200021021 is a deficient number, since it is larger than the sum of its proper divisors (2603437851619).

21000200021021 is a wasteful number, since it uses less digits than its factorization.

21000200021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14139596.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21000200021021 its reverse (12012000200012), we get a palindrome (33012200221033).

The spelling of 21000200021021 in words is "twenty-one trillion, two hundred million, twenty-one thousand, twenty-one".