21216361556636 has 24 divisors (see below), whose sum is σ = 39088369111680. Its totient is φ = 10048416034032.

The previous prime is 21216361556563. The next prime is 21216361556639. The reversal of 21216361556636 is 63665516361212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21216361556639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19458026 + ... + 20519441.

It is an arithmetic number, because the mean of its divisors is an integer number (1628682046320).

Almost surely, 2^{21216361556636} is an apocalyptic number.

It is an amenable number.

21216361556636 is a deficient number, since it is larger than the sum of its proper divisors (17872007555044).

21216361556636 is a wasteful number, since it uses less digits than its factorization.

21216361556636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39984473 (or 39984471 counting only the distinct ones).

The product of its digits is 6998400, while the sum is 53.

The spelling of 21216361556636 in words is "twenty-one trillion, two hundred sixteen billion, three hundred sixty-one million, five hundred fifty-six thousand, six hundred thirty-six".