21323024021 has 4 divisors (see below), whose sum is σ = 22963256652. Its totient is φ = 19682791392.

The previous prime is 21323024017. The next prime is 21323024081. The reversal of 21323024021 is 12042032312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4523235025 + 16799788996 = 67255^2 + 129614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323024021 - 2² = 21323024017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21323023984 and 21323024002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323024011) 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, 820116296 + ... + 820116321.

It is an arithmetic number, because the mean of its divisors is an integer number (5740814163).

Almost surely, 2^21323024021 is an apocalyptic number.

It is an amenable number.

21323024021 is a deficient number, since it is larger than the sum of its proper divisors (1640232631).

21323024021 is a wasteful number, since it uses less digits than its factorization.

21323024021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1640232630.

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21323024021 its reverse (12042032312), we get a palindrome (33365056333).

The spelling of 21323024021 in words is "twenty-one billion, three hundred twenty-three million, twenty-four thousand, twenty-one".