21816604812 has 12 divisors (see below), whose sum is σ = 50905411256. Its totient is φ = 7272201600.

The previous prime is 21816604811. The next prime is 21816604819. The reversal of 21816604812 is 21840661812.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (21816604811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 909025189 + ... + 909025212.

Almost surely, 2^21816604812 is an apocalyptic number.

It is an amenable number.

21816604812 is an abundant number, since it is smaller than the sum of its proper divisors (29088806444).

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

21816604812 is a wasteful number, since it uses less digits than its factorization.

21816604812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1818050408 (or 1818050406 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 39.

The spelling of 21816604812 in words is "twenty-one billion, eight hundred sixteen million, six hundred four thousand, eight hundred twelve".