21002311021 has 4 divisors (see below), whose sum is σ = 21013189344. Its totient is φ = 20991432700.

The previous prime is 21002311019. The next prime is 21002311039. The reversal of 21002311021 is 12011320012.

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 21002311021 - 2¹ = 21002311019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002310992 and 21002311010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002311051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5436265 + ... + 5440126.

It is an arithmetic number, because the mean of its divisors is an integer number (5253297336).

Almost surely, 2^21002311021 is an apocalyptic number.

It is an amenable number.

21002311021 is a deficient number, since it is larger than the sum of its proper divisors (10878323).

21002311021 is a wasteful number, since it uses less digits than its factorization.

21002311021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10878322.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21002311021 its reverse (12011320012), we get a palindrome (33013631033).

The spelling of 21002311021 in words is "twenty-one billion, two million, three hundred eleven thousand, twenty-one".