21305505812 has 48 divisors (see below), whose sum is σ = 38507374080. Its totient is φ = 10309575168.

The previous prime is 21305505773. The next prime is 21305505821. The reversal of 21305505812 is 21850550312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14867048 + ... + 14868480.

It is an arithmetic number, because the mean of its divisors is an integer number (802236960).

Almost surely, 2^21305505812 is an apocalyptic number.

It is an amenable number.

21305505812 is a deficient number, since it is larger than the sum of its proper divisors (17201868268).

21305505812 is a wasteful number, since it uses less digits than its factorization.

21305505812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2432 (or 2430 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 32.

The spelling of 21305505812 in words is "twenty-one billion, three hundred five million, five hundred five thousand, eight hundred twelve".