21645244608 has 112 divisors (see below), whose sum is σ = 61999343616. Its totient is φ = 6625059840.

The previous prime is 21645244597. The next prime is 21645244637. The reversal of 21645244608 is 80644254612.

It is a super-2 number, since 2×21645244608² (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 21645244608.

It is an unprimeable number.

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, 454035 + ... + 499437.

It is an arithmetic number, because the mean of its divisors is an integer number (553565568).

Almost surely, 2^21645244608 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 21645244608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30999671808).

21645244608 is an abundant number, since it is smaller than the sum of its proper divisors (40354099008).

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

21645244608 is a wasteful number, since it uses less digits than its factorization.

21645244608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45622 (or 45612 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 42.

The spelling of 21645244608 in words is "twenty-one billion, six hundred forty-five million, two hundred forty-four thousand, six hundred eight".