21305720063 has 2 divisors, whose sum is σ = 21305720064. Its totient is φ = 21305720062.

The previous prime is 21305720047. The next prime is 21305720077. The reversal of 21305720063 is 36002750312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21305720063 - 2⁴ = 21305720047 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21305720363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652860031 + 10652860032.

It is an arithmetic number, because the mean of its divisors is an integer number (10652860032).

Almost surely, 2^21305720063 is an apocalyptic number.

21305720063 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305720063 is an equidigital number, since it uses as much as digits as its factorization.

21305720063 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 29.

The spelling of 21305720063 in words is "twenty-one billion, three hundred five million, seven hundred twenty thousand, sixty-three".