21000001221021 has 16 divisors (see below), whose sum is σ = 29705762201600. Its totient is φ = 13158724341168.

The previous prime is 21000001220969. The next prime is 21000001221047. The reversal of 21000001221021 is 12012210000012.

It is not a de Polignac number, because 21000001221021 - 2²¹ = 20999999123869 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000001220988 and 21000001221006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000001228021) 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, 1450469431 + ... + 1450483908.

It is an arithmetic number, because the mean of its divisors is an integer number (1856610137600).

Almost surely, 2^{21000001221021} is an apocalyptic number.

It is an amenable number.

21000001221021 is a deficient number, since it is larger than the sum of its proper divisors (8705760980579).

21000001221021 is a wasteful number, since it uses less digits than its factorization.

21000001221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2900953488.

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

Adding to 21000001221021 its reverse (12012210000012), we get a palindrome (33012211221033).

The spelling of 21000001221021 in words is "twenty-one trillion, one million, two hundred twenty-one thousand, twenty-one".