21115516445563 has 8 divisors (see below), whose sum is σ = 21726931554576. Its totient is φ = 20511990564000.

The previous prime is 21115516445549. The next prime is 21115516445581. The reversal of 21115516445563 is 36554461551112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21115516445563 - 2²⁵ = 21115482891131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115516445063) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1972301433 + ... + 1972312138.

It is an arithmetic number, because the mean of its divisors is an integer number (2715866444322).

Almost surely, 2^{21115516445563} is an apocalyptic number.

21115516445563 is a deficient number, since it is larger than the sum of its proper divisors (611415109013).

21115516445563 is a wasteful number, since it uses less digits than its factorization.

21115516445563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3944613725.

The product of its digits is 2160000, while the sum is 49.

Adding to 21115516445563 its reverse (36554461551112), we get a palindrome (57669977996675).

The spelling of 21115516445563 in words is "twenty-one trillion, one hundred fifteen billion, five hundred sixteen million, four hundred forty-five thousand, five hundred sixty-three".