21303120021 has 4 divisors (see below), whose sum is σ = 28404160032. Its totient is φ = 14202080012.

The previous prime is 21303119987. The next prime is 21303120043. The reversal of 21303120021 is 12002130312.

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 21303120021 - 2¹¹ = 21303117973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303120061) 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, 3550520001 + ... + 3550520006.

It is an arithmetic number, because the mean of its divisors is an integer number (7101040008).

Almost surely, 2^21303120021 is an apocalyptic number.

It is an amenable number.

21303120021 is a deficient number, since it is larger than the sum of its proper divisors (7101040011).

21303120021 is an equidigital number, since it uses as much as digits as its factorization.

21303120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7101040010.

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 21303120021 its reverse (12002130312), we get a palindrome (33305250333).

The spelling of 21303120021 in words is "twenty-one billion, three hundred three million, one hundred twenty thousand, twenty-one".