21115515506365 has 48 divisors (see below), whose sum is σ = 29719165641984. Its totient is φ = 14359969008000.

The previous prime is 21115515506359. The next prime is 21115515506369. The reversal of 21115515506365 is 56360551551112.

It is not a de Polignac number, because 21115515506365 - 2³ = 21115515506357 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115515506369) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15625890 + ... + 16923340.

It is an arithmetic number, because the mean of its divisors is an integer number (619149284208).

Almost surely, 2^{21115515506365} is an apocalyptic number.

It is an amenable number.

21115515506365 is a deficient number, since it is larger than the sum of its proper divisors (8603650135619).

21115515506365 is a wasteful number, since it uses less digits than its factorization.

21115515506365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1298018 (or 1298011 counting only the distinct ones).

The product of its (nonzero) digits is 675000, while the sum is 46.

The spelling of 21115515506365 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred six thousand, three hundred sixty-five".