21812560864 has 48 divisors (see below), whose sum is σ = 44130861936. Its totient is φ = 10605081600.

The previous prime is 21812560843. The next prime is 21812560867. The reversal of 21812560864 is 46806521812.

It is a super-2 number, since 2×21812560864² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21812560864.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21812560867) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2376444 + ... + 2385604.

It is an arithmetic number, because the mean of its divisors is an integer number (919392957).

Almost surely, 2^21812560864 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 21812560864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22065430968).

21812560864 is an abundant number, since it is smaller than the sum of its proper divisors (22318301072).

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

21812560864 is a wasteful number, since it uses less digits than its factorization.

21812560864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11219 (or 11211 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 43.

The spelling of 21812560864 in words is "twenty-one billion, eight hundred twelve million, five hundred sixty thousand, eight hundred sixty-four".