21115515506369 has 2 divisors, whose sum is σ = 21115515506370. Its totient is φ = 21115515506368.

The previous prime is 21115515506359. The next prime is 21115515506377. The reversal of 21115515506369 is 96360551551112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20121396833344 + 994118673025 = 4485688^2 + 997055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115515506369 - 2¹² = 21115515502273 is a prime.

It is a super-2 number, since 2×21115515506369² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21115515506359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557757753184 + 10557757753185.

It is an arithmetic number, because the mean of its divisors is an integer number (10557757753185).

Almost surely, 2^{21115515506369} is an apocalyptic number.

It is an amenable number.

21115515506369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115515506369 is an equidigital number, since it uses as much as digits as its factorization.

21115515506369 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1215000, while the sum is 50.

The spelling of 21115515506369 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred six thousand, three hundred sixty-nine".