21066436415539 has 2 divisors, whose sum is σ = 21066436415540. Its totient is φ = 21066436415538.

The previous prime is 21066436415509. The next prime is 21066436415543. The reversal of 21066436415539 is 93551463466012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21066436415539 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21066436415539.

It is not a weakly prime, because it can be changed into another prime (21066436415509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10533218207769 + 10533218207770.

It is an arithmetic number, because the mean of its divisors is an integer number (10533218207770).

Almost surely, 2^{21066436415539} is an apocalyptic number.

21066436415539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21066436415539 is an equidigital number, since it uses as much as digits as its factorization.

21066436415539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13996800, while the sum is 55.

The spelling of 21066436415539 in words is "twenty-one trillion, sixty-six billion, four hundred thirty-six million, four hundred fifteen thousand, five hundred thirty-nine".