21115116663 has 4 divisors (see below), whose sum is σ = 28153488888. Its totient is φ = 14076744440.

The previous prime is 21115116653. The next prime is 21115116677. The reversal of 21115116663 is 36661151112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21115116663 - 2¹² = 21115112567 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115116653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3519186108 + ... + 3519186113.

It is an arithmetic number, because the mean of its divisors is an integer number (7038372222).

Almost surely, 2^21115116663 is an apocalyptic number.

21115116663 is a deficient number, since it is larger than the sum of its proper divisors (7038372225).

21115116663 is an equidigital number, since it uses as much as digits as its factorization.

21115116663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7038372224.

The product of its digits is 6480, while the sum is 33.

Adding to 21115116663 its reverse (36661151112), we get a palindrome (57776267775).

The spelling of 21115116663 in words is "twenty-one billion, one hundred fifteen million, one hundred sixteen thousand, six hundred sixty-three".