21020053021 has 4 divisors (see below), whose sum is σ = 22930966944. Its totient is φ = 19109139100.

The previous prime is 21020052973. The next prime is 21020053111. The reversal of 21020053021 is 12035002012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21020053021 - 2¹⁵ = 21020020253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020052986 and 21020053004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020053321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 955456945 + ... + 955456966.

It is an arithmetic number, because the mean of its divisors is an integer number (5732741736).

Almost surely, 2^21020053021 is an apocalyptic number.

It is an amenable number.

21020053021 is a deficient number, since it is larger than the sum of its proper divisors (1910913923).

21020053021 is a wasteful number, since it uses less digits than its factorization.

21020053021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1910913922.

The product of its (nonzero) digits is 120, while the sum is 16.

Adding to 21020053021 its reverse (12035002012), we get a palindrome (33055055033).

The spelling of 21020053021 in words is "twenty-one billion, twenty million, fifty-three thousand, twenty-one".