21115515506364 has 144 divisors (see below), whose sum is σ = 55189769098464. Its totient is φ = 6802754112000.

The previous prime is 21115515506359. The next prime is 21115515506369. The reversal of 21115515506364 is 46360551551112.

21115515506364 is a `hidden beast` number, since 2 + 1 + 1 + 1 + 5 + 5 + 1 + 5 + 5 + 0 + 636 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (21115515506359) and next prime (21115515506369).

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

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 272163082 + ... + 272240654.

It is an arithmetic number, because the mean of its divisors is an integer number (383262285406).

Almost surely, 2^{21115515506364} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21115515506364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27594884549232).

21115515506364 is an abundant number, since it is smaller than the sum of its proper divisors (34074253592100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21115515506364 is a wasteful number, since it uses less digits than its factorization.

21115515506364 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79468 (or 79463 counting only the distinct ones).

The product of its (nonzero) digits is 540000, while the sum is 45.

The spelling of 21115515506364 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred six thousand, three hundred sixty-four".