21302123021 has 2 divisors, whose sum is σ = 21302123022. Its totient is φ = 21302123020.

The previous prime is 21302122993. The next prime is 21302123053. The reversal of 21302123021 is 12032120312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15577536100 + 5724586921 = 124810^2 + 75661^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302123021 - 2³⁰ = 20228381197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21302153021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651061510 + 10651061511.

It is an arithmetic number, because the mean of its divisors is an integer number (10651061511).

Almost surely, 2^21302123021 is an apocalyptic number.

It is an amenable number.

21302123021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302123021 is an equidigital number, since it uses as much as digits as its factorization.

21302123021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21302123021 its reverse (12032120312), we get a palindrome (33334243333).

The spelling of 21302123021 in words is "twenty-one billion, three hundred two million, one hundred twenty-three thousand, twenty-one".