21344009021 has 2 divisors, whose sum is σ = 21344009022. Its totient is φ = 21344009020.

The previous prime is 21344009017. The next prime is 21344009047. The reversal of 21344009021 is 12090044312.

It is an a-pointer prime, because the next prime (21344009047) can be obtained adding 21344009021 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15015806521 + 6328202500 = 122539^2 + 79550^2 .

It is a cyclic number.

It is not a de Polignac number, because 21344009021 - 2² = 21344009017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21344009221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672004510 + 10672004511.

It is an arithmetic number, because the mean of its divisors is an integer number (10672004511).

Almost surely, 2^21344009021 is an apocalyptic number.

It is an amenable number.

21344009021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21344009021 is an equidigital number, since it uses as much as digits as its factorization.

21344009021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

The spelling of 21344009021 in words is "twenty-one billion, three hundred forty-four million, nine thousand, twenty-one".