21616231664655 has 128 divisors (see below), whose sum is σ = 39404778393600. Its totient is φ = 11238811803648.

The previous prime is 21616231664647. The next prime is 21616231664669. The reversal of 21616231664655 is 55646613261612.

21616231664655 is a `hidden beast` number, since 2 + 1 + 6 + 1 + 623 + 1 + 6 + 6 + 4 + 6 + 5 + 5 = 666.

It is not a de Polignac number, because 21616231664655 - 2³ = 21616231664647 is a prime.

It is a super-2 number, since 2×21616231664655² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1186196874 + ... + 1186215096.

It is an arithmetic number, because the mean of its divisors is an integer number (307849831200).

Almost surely, 2^{21616231664655} is an apocalyptic number.

21616231664655 is a deficient number, since it is larger than the sum of its proper divisors (17788546728945).

21616231664655 is a wasteful number, since it uses less digits than its factorization.

21616231664655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19342 (or 19336 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 54.

The spelling of 21616231664655 in words is "twenty-one trillion, six hundred sixteen billion, two hundred thirty-one million, six hundred sixty-four thousand, six hundred fifty-five".