21002309893 has 2 divisors, whose sum is σ = 21002309894. Its totient is φ = 21002309892.

The previous prime is 21002309831. The next prime is 21002309897. The reversal of 21002309893 is 39890320012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12644327809 + 8357982084 = 112447^2 + 91422^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002309893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002309897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501154946 + 10501154947.

It is an arithmetic number, because the mean of its divisors is an integer number (10501154947).

Almost surely, 2^21002309893 is an apocalyptic number.

It is an amenable number.

21002309893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002309893 is an equidigital number, since it uses as much as digits as its factorization.

21002309893 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 37.

The spelling of 21002309893 in words is "twenty-one billion, two million, three hundred nine thousand, eight hundred ninety-three".