21115416516644 has 12 divisors (see below), whose sum is σ = 37044128480268. Its totient is φ = 10531379808000.

The previous prime is 21115416516641. The next prime is 21115416516661. The reversal of 21115416516644 is 44661561451112.

It can be written as a sum of positive squares in 2 ways, for example, as 13321492619044 + 7793923897600 = 3649862^2 + 2791760^2 .

It is not an unprimeable number, because it can be changed into a prime (21115416516641) 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, 6582110777 + ... + 6582113984.

It is an arithmetic number, because the mean of its divisors is an integer number (3087010706689).

Almost surely, 2^{21115416516644} is an apocalyptic number.

It is an amenable number.

21115416516644 is a deficient number, since it is larger than the sum of its proper divisors (15928711963624).

21115416516644 is a wasteful number, since it uses less digits than its factorization.

21115416516644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13164225166 (or 13164225164 counting only the distinct ones).

The product of its digits is 691200, while the sum is 47.

Adding to 21115416516644 its reverse (44661561451112), we get a palindrome (65776977967756).

The spelling of 21115416516644 in words is "twenty-one trillion, one hundred fifteen billion, four hundred sixteen million, five hundred sixteen thousand, six hundred forty-four".