21204771812 has 96 divisors (see below), whose sum is σ = 44351193600. Its totient is φ = 8679186432.

The previous prime is 21204771811. The next prime is 21204771821. The reversal of 21204771812 is 21817740212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21204771811) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42156353 + ... + 42156855.

It is an arithmetic number, because the mean of its divisors is an integer number (461991600).

Almost surely, 2^21204771812 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21204771812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22175596800).

21204771812 is an abundant number, since it is smaller than the sum of its proper divisors (23146421788).

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

21204771812 is a wasteful number, since it uses less digits than its factorization.

21204771812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1005 (or 1003 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 35.

The spelling of 21204771812 in words is "twenty-one billion, two hundred four million, seven hundred seventy-one thousand, eight hundred twelve".