21561216036 has 48 divisors (see below), whose sum is σ = 52996493760. Its totient is φ = 6803775360.

The previous prime is 21561216031. The next prime is 21561216073. The reversal of 21561216036 is 63061216512.

It is a junction number, because it is equal to n+sod(n) for n = 21561215988 and 21561216006.

It is not an unprimeable number, because it can be changed into a prime (21561216031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 280630 + ... + 349106.

It is an arithmetic number, because the mean of its divisors is an integer number (1104093620).

Almost surely, 2^21561216036 is an apocalyptic number.

It is an amenable number.

21561216036 is an abundant number, since it is smaller than the sum of its proper divisors (31435277724).

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

21561216036 is a wasteful number, since it uses less digits than its factorization.

21561216036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69884 (or 69882 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The spelling of 21561216036 in words is "twenty-one billion, five hundred sixty-one million, two hundred sixteen thousand, thirty-six".