21369049717 has 2 divisors, whose sum is σ = 21369049718. Its totient is φ = 21369049716.

The previous prime is 21369049699. The next prime is 21369049733. The reversal of 21369049717 is 71794096312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13569687121 + 7799362596 = 116489^2 + 88314^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21369049717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21369049217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684524858 + 10684524859.

It is an arithmetic number, because the mean of its divisors is an integer number (10684524859).

Almost surely, 2^21369049717 is an apocalyptic number.

It is an amenable number.

21369049717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21369049717 is an equidigital number, since it uses as much as digits as its factorization.

21369049717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 571536, while the sum is 49.

The spelling of 21369049717 in words is "twenty-one billion, three hundred sixty-nine million, forty-nine thousand, seven hundred seventeen".