21365564501539 has 2 divisors, whose sum is σ = 21365564501540. Its totient is φ = 21365564501538.

The previous prime is 21365564501419. The next prime is 21365564501549. The reversal of 21365564501539 is 93510546556312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21365564501539 - 2¹³ = 21365564493347 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21365564501539.

It is not a weakly prime, because it can be changed into another prime (21365564501549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682782250769 + 10682782250770.

It is an arithmetic number, because the mean of its divisors is an integer number (10682782250770).

Almost surely, 2^{21365564501539} is an apocalyptic number.

21365564501539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365564501539 is an equidigital number, since it uses as much as digits as its factorization.

21365564501539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14580000, while the sum is 55.

The spelling of 21365564501539 in words is "twenty-one trillion, three hundred sixty-five billion, five hundred sixty-four million, five hundred one thousand, five hundred thirty-nine".