21023113021 has 4 divisors (see below), whose sum is σ = 21188649472. Its totient is φ = 20857576572.

The previous prime is 21023113003. The next prime is 21023113031. The reversal of 21023113021 is 12031132012.

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 a de Polignac number, because none of the positive numbers 2^k-21023113021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21023112986 and 21023113004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023113031) 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, 82768035 + ... + 82768288.

It is an arithmetic number, because the mean of its divisors is an integer number (5297162368).

Almost surely, 2^21023113021 is an apocalyptic number.

It is an amenable number.

21023113021 is a deficient number, since it is larger than the sum of its proper divisors (165536451).

21023113021 is a wasteful number, since it uses less digits than its factorization.

21023113021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165536450.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21023113021 its reverse (12031132012), we get a palindrome (33054245033).

The spelling of 21023113021 in words is "twenty-one billion, twenty-three million, one hundred thirteen thousand, twenty-one".