21305460554509 has 2 divisors, whose sum is σ = 21305460554510. Its totient is φ = 21305460554508.

The previous prime is 21305460554467. The next prime is 21305460554519. The reversal of 21305460554509 is 90545506450312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21248827026025 + 56633528484 = 4609645^2 + 237978^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21305460554509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21305460554519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652730277254 + 10652730277255.

It is an arithmetic number, because the mean of its divisors is an integer number (10652730277255).

Almost surely, 2^{21305460554509} is an apocalyptic number.

It is an amenable number.

21305460554509 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305460554509 is an equidigital number, since it uses as much as digits as its factorization.

21305460554509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240000, while the sum is 49.

The spelling of 21305460554509 in words is "twenty-one trillion, three hundred five billion, four hundred sixty million, five hundred fifty-four thousand, five hundred nine".