21115530216565 has 32 divisors (see below), whose sum is σ = 26471590041600. Its totient is φ = 16138869721920.

The previous prime is 21115530216523. The next prime is 21115530216577. The reversal of 21115530216565 is 56561203551112.

It is a happy number.

It is not a de Polignac number, because 21115530216565 - 2³⁷ = 20978091263093 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 372965110 + ... + 373021720.

It is an arithmetic number, because the mean of its divisors is an integer number (827237188800).

Almost surely, 2^{21115530216565} is an apocalyptic number.

It is an amenable number.

21115530216565 is a deficient number, since it is larger than the sum of its proper divisors (5356059825035).

21115530216565 is a wasteful number, since it uses less digits than its factorization.

21115530216565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60417.

The product of its (nonzero) digits is 270000, while the sum is 43.

Adding to 21115530216565 its reverse (56561203551112), we get a palindrome (77676733767677).

The spelling of 21115530216565 in words is "twenty-one trillion, one hundred fifteen billion, five hundred thirty million, two hundred sixteen thousand, five hundred sixty-five".