21323030021 has 2 divisors, whose sum is σ = 21323030022. Its totient is φ = 21323030020.

The previous prime is 21323029999. The next prime is 21323030081. The reversal of 21323030021 is 12003032312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21253557796 + 69472225 = 145786^2 + 8335^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323030021 - 2²⁶ = 21255921157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21323030081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661515010 + 10661515011.

It is an arithmetic number, because the mean of its divisors is an integer number (10661515011).

Almost surely, 2^21323030021 is an apocalyptic number.

It is an amenable number.

21323030021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323030021 is an equidigital number, since it uses as much as digits as its factorization.

21323030021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 17.

Adding to 21323030021 its reverse (12003032312), we get a palindrome (33326062333).

The spelling of 21323030021 in words is "twenty-one billion, three hundred twenty-three million, thirty thousand, twenty-one".