21023340021 has 8 divisors (see below), whose sum is σ = 31145688960. Its totient is φ = 14015559996.

The previous prime is 21023340017. The next prime is 21023340043. The reversal of 21023340021 is 12004332012.

21023340021 is a `hidden beast` number, since 2 + 10 + 233 + 400 + 21 = 666.

It is not a de Polignac number, because 21023340021 - 2² = 21023340017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21023339976 and 21023340003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023340061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389321085 + ... + 389321138.

It is an arithmetic number, because the mean of its divisors is an integer number (3893211120).

Almost surely, 2^21023340021 is an apocalyptic number.

It is an amenable number.

21023340021 is a deficient number, since it is larger than the sum of its proper divisors (10122348939).

21023340021 is an equidigital number, since it uses as much as digits as its factorization.

21023340021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778642232 (or 778642226 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21023340021 its reverse (12004332012), we get a palindrome (33027672033).

The spelling of 21023340021 in words is "twenty-one billion, twenty-three million, three hundred forty thousand, twenty-one".