21020121021 has 16 divisors (see below), whose sum is σ = 30058568640. Its totient is φ = 13025376000.

The previous prime is 21020121007. The next prime is 21020121029. The reversal of 21020121021 is 12012102012.

It is not a de Polignac number, because 21020121021 - 2²¹ = 21018023869 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020120988 and 21020121006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020121029) 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, 3475980 + ... + 3482021.

It is an arithmetic number, because the mean of its divisors is an integer number (1878660540).

Almost surely, 2^21020121021 is an apocalyptic number.

It is an amenable number.

21020121021 is a deficient number, since it is larger than the sum of its proper divisors (9038447619).

21020121021 is a wasteful number, since it uses less digits than its factorization.

21020121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6958076.

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

Adding to 21020121021 its reverse (12012102012), we get a palindrome (33032223033).

The spelling of 21020121021 in words is "twenty-one billion, twenty million, one hundred twenty-one thousand, twenty-one".