21615555411616 has 24 divisors (see below), whose sum is σ = 43593566785524. Its totient is φ = 10544173370880.

The previous prime is 21615555411559. The next prime is 21615555411629. The reversal of 21615555411616 is 61611455551612.

It can be written as a sum of positive squares in 2 ways, for example, as 17783122736016 + 3832432675600 = 4217004^2 + 1957660^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21615555411616.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8237634135 + ... + 8237636758.

Almost surely, 2^{21615555411616} is an apocalyptic number.

It is an amenable number.

21615555411616 is an abundant number, since it is smaller than the sum of its proper divisors (21978011373908).

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

21615555411616 is a wasteful number, since it uses less digits than its factorization.

21615555411616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16475270944 (or 16475270936 counting only the distinct ones).

The product of its digits is 1080000, while the sum is 49.

The spelling of 21615555411616 in words is "twenty-one trillion, six hundred fifteen billion, five hundred fifty-five million, four hundred eleven thousand, six hundred sixteen".