21365971799 has 2 divisors, whose sum is σ = 21365971800. Its totient is φ = 21365971798.

The previous prime is 21365971793. The next prime is 21365971843. The reversal of 21365971799 is 99717956312.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21365971799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21365971793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682985899 + 10682985900.

It is an arithmetic number, because the mean of its divisors is an integer number (10682985900).

Almost surely, 2^21365971799 is an apocalyptic number.

21365971799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365971799 is an equidigital number, since it uses as much as digits as its factorization.

21365971799 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6429780, while the sum is 59.

The spelling of 21365971799 in words is "twenty-one billion, three hundred sixty-five million, nine hundred seventy-one thousand, seven hundred ninety-nine".